DSP-10 User's Manual V396

Transceiver Operation

This Chapter covers user information about the general operation of the DSP-10.
SSB Operation Let's start a tour of the DSP10 operation by looking at receiving and transmitting a SSB signal. We assume that you have gotten the hardware working, that it is properly connected , and have the software loaded. So the DSP10 screen should be displayed and the clock in the lower left corner should be updating. We'll also assume that you are using the default settings for the UHFA.CFG Configuration File , at least as a start.

USB is the default mode and should be indicated on the screen. If not, use ALT-M mode selection to bring up the Mode to USB, the standard sideband for VHF operation. If this mode is is not available check the configuration file variable, mode_mask .

SSB Frequency - The frequency can be set by the F9 and F10 keys, along with the modifiers CTRL, ALT and SHIFT. The display is the transmit frequency for zero audio frequency, meaning that the upper sideband extends from this frequency upward by about 3 kHz. You can also change the receive frequency with RIT . This does not change the indicated frequency, since the displayed frequency is the transmit frequency.

Audio Settings

 Now, if the audio gain is turned up, you are ready to receive signals. This is a good time to explore the use of the cursor keys to change frequency and audio gain. The left and right cursor keys should lower and raise the frequency by 50 Hz. These same keys, along with the SHIFT key will change the frequency by 1 kHz. Most people find this makes a tuning arrangement that rivals a knob! If the tuning steps are not what you want, they can be altered in value . Additionally, the audio gain can be changed by the up/down arrows. The default values are 2 dB (10 dB with shift) but they can also be altered. Try "Page Down" key; it mutes the audio on and off.

A variety of audio filters are available for reception. This includes the ability to design a custom filter to suit your desires.

Transmit SSB - Transmitting USB requires having the microphone connected, of course. Additionally, the push-to-talk comes in two styles. The default is all software and serial link controlled. This introduces an annoying delay, but works fine. You will want to install the hardware PTT connection to the PC; this goes through the same serial cable, but does require minor changes to the EZ-KIT Lite wiring. You can also always use the "Home" key to toggle transmit and receive (be sure that the SCRL Lock is off!).

There are three interacting controls for the audio level. The hardware audio gain should be set first. If a 'scope is available, look at the audio level on the line ADC_L, which may be most accessible at the feed-through capacitor C216.The hardware gain should be set so that the level never exceeds 1 Volt, peak-to-peak, using your normal speech level. Alternatively, watch the D/A level bar graph (SCRL F3) and be sure the last bar does not light, but the next to right one does on peaks.
Next, using the CW or FM modes, set the "Xmit Pwr, SCRL-O and SCRL-P, for the desired output to drive the following transverter or amplifier. A power indicator, such as the diode detector in Fig 12 of the October 1999 QST article may be helpful for this experimentation.   If the resulting setting is above 95, it is best to reduce the power level to 95.  Failure to do so will result in a warning message, "W17 Excess Pwr."  Two problems can result.  First, the RF amplifiers are being challenged for ouput, and gain compression may cause splatter.  The exact point of concern here may vary from one radio to another, but Xmit Pwr=95 should be a safe point.  In addition, the clipping and filtering used needs a fraction of a dB for  overshoot in the filter, and a setting of 100 does not allow that, whereas 99 does..

 Next, return to USB or LSB, and adjust the mike gain by watching the clipping level on the left side, and keep the clipping to around 0 to 6 dB.  The maximum clipping is 12 dB, and exceeding this level can cause splatter.

On-the-air tests will be the final test of this level to be sure that you are not over-driving either the DSP10 or any follow-on amplifiers.

Other improvement that can come from over-the-air tests using the transmit microphone equalizer.

CW Operation

CW operation starts with selection of CW (or as we can explore later, LTI) modes. ALT-M goes through all modes allowed by the variable mode_mask in the Configuration File . The CW mode cannot be masked, and is always available. CW Keying - A CW key can be plugged into the DSP-10. This is not a paddle, but just a simple straight key.Alternatively, the right-hand ALT key can be used as a straight key. Not all keyboards have that ALT key, however. For those not wanting to use a key, CW can be sent directly from the keyboard. This can be typed in while in either Transmit or Receive. It will not be sent unless in Transmit. Most punctuation marks are available, as well as some of the specialized symbols, such as AR and SK. These are listed in the CW section of the Keyboard Commands . Capital and lower-case letters are treated identically.

 Up to10  CW messages can be saved in the UHFA.CFG for loading to the CW transmit buffer.. CTRL-ALT-SHIFT-3 will place the following message in the transmit buffer. If the DSP-10 is in transmit, the message will be sent immediately. If not in transmit, it will wait until transmit is started.

cwmsg 3  |@%CQ CQ DE W7SZ W7SZ W7SZ [ K!|

Seven special control characters are available in CW, but may be particularly useful embedded into a
message, as follows:

# first and last elements of a looped meassage
@ breaks any #...# loop that may be active.
% clears the CW sending buffer, immediately
~ a programmable length" key down" default value is 10 (seconds)
{ key down one second
} key up one second (kinda like a space)
! Takes the radio out of Transmit and places it into Receive.

Thus, for instance, a CQ message might be:

cwmsg 3 |@%CQ CQ DE W7SZ W7SZ W7SZ [ K!|

This would first clear any loop and the transmit buffer. (this is generally a good way to start any precanned message; it is ignored if no loop is running). Next the CQ message is sent, followed by '[' for AR and a 'K'. Finally the radio is put into receive with a '!'. That's it the message has been sent.

If we want to have a message that can be repeated by the home key we can add # to the begining and end of the message

cwmsg 1 |@%# CQ CQ DE W7SZ W7SZ W7SZ [ K!#|

Now the message wants to loop between the two #'s forever, except we sent the machine to receive with the !. All that's needed to send this again, is to hit the HOME key. If we need to type a message from the keyboard, we must first clear the transmit buffer by SHIFT-DELETE, else the message will send every time we try to transmit.. Running this message with the BCN on will cause the DSP-10 to switch bqack to receive momentarily, then send the message again.. No harm comes of this, but it seems silly. Use of the @ and % is highly recommended unless you have no more than one "canned" message.

There are many ways to use the transmit message buffer and the "beacon" T/R together.

If you want to call a CQ every now and then, find the length of time needed to call a CQ.. if this is 15 seconds for instance, and we want to listen for 30 seconds after the CQ then......... set the times in SCRL F2 to 15, 30, 0 and move the canned message to the transmit buffer.Beacon TRANSMIT is initiated with ALT H, NOT the HOME key

cwmsg 4 |@%cq cq cq de kd7ts cn87 #|

15 and 30 seconds do not add up to an even submultiple of an hour, so each CQ will be sent in a different part of each minute.
Beacon timing can be saved in a memory that you create for this particular use. The message is stored in UHFA.CFG.

Another use is for filling air time with "key down" and an ID every minute. By timing the ID length -- SPACE call SPACE, we can determine how long we can hold the key down. If the call and two spaces take 7 seconds, then we can change the (tilde) in UHFA.CFG to 53 (cw_longkey 53). These are the ingredients for a one minute loop.

cwmsg 5 |@%#~ kd7ts #|

This will repeat forever ! To complete this we use the "beacon" T/R set for five minute transmit and five minute receive. In the SCRL F2 dialog box we put in 300, 300,0. This tells the DSP-10 to transmit for 300 seconds ( five minutes) starting at 0, 10, 20, 30, 40, 50 minutes and switch to receive at 5 15 25 35 45 55 minutes. Beacon TRANSMIT is initiated with ALT H, NOT the HOME key.

CW Sidetone and Offset - In the CW mode there are several special display items. Between the "Mode" and "CW" on the left there are two numbers in beige. The first is the side-tone level that is adjustable by Scrl S and Scrl D commands. This ranges from 0 to 100. The second number is the CW offset value. This is the frequency shift that occurs between transmit and receive. The displayed frequency is the actual transmit frequency. In CW the receive "zero-beat" frequency is lower by the CW-offset and reception is in USB. The CW-offset is set by the Scrl C and Scrl V commands. In addition, at the bottom of the spectral display there is a small red line that shows the CW-offset. If the received signal is lined up with this mark you will be transmitting on the same frequency as the one you are receiving. Most often, you will want the CW-offset to be the same as the center frequency of the audio filters.

While on the subject of CW, the side-tone frequency tracks the CW Offset. If the pitch being received is the same as that of the side-tone, you will be transmitting on the same frequency as the station being received. The side-tone is only available in the right speaker since the left side D/A is being used for the transmit I-F.

CW Speed - The "CW Speed" applies only to transmit. There is no automatic CW reception implemented. The CW speed weighting is standard 1-3-5 for the higher speeds and gradually changes to faster characters and longer spaces for speeds below about 13 WPM. For those desiring to play with such things, all the weighting and speeds are programmable by recompiling the program. Presently the speeds for conventional CW are 5 to 75 WPM, in various sized steps. In addition, to support experiments in Very Slow CW, speeds of 0.5 and 1 WPM are available. These are normally read by watching a spectral waterfall.

Transmit/Receive - Transmit/Receive toggling is most easily done with the HOME key (be sure that SCRL-Lock is off). However, the PTT connection from the microphone is active. The transmit audio is, of course, turned off.

A variety of audio filters are availables for reception.

FM Operation

FM operation with the DSP-10 is very parallel to commercial radios. This supports NBFM, has a squelch and a few "channels" which are referred to as Memories, which include FM offsets and associated tones. No scanning provision is included. Mode selection is done with the ALT-M key combination. Be sure that the mode_mask has been set to include FM (an 8 in the sum).

FM Frequencies - FM frequencies tune in even 5 kHz steps. The tuning controls using the F9 and F10 keys will only allow 5 kHz or larger steps; any step less than 5 kHz will shift at the larger resolution. The display is only to 1 kHz resolution. RIT settings are not used in FM, although they continue to appear.

For channelized operation, any VFO or Memory may be used. VFOs remember the last saved frequency and mode, along with the FM offset, and FM tone data. Memories will return to the preset frequency and mode, as well as almost any DSP-10 configuration, if needed.

FM Audio

There is a separate gain control for FM that comes and goes with that mode. The mute will pick up the wrong AF gain if you change into or out of FM while muted.

VFO Operation - There are 20 VFOs available. Each of these is recorded in the UHFA.CFG configuration file For simplex operation, the definition of a VFO requires no editing of the configuration file. For example, operation on 146.52 using VFO 3 would be set up by selecting that VFO, with Ctrl-Alt-D (A is 0, B is 1, etc.), selecting the FM mode, and tuning the radio to 146.520 MHz. Using any other VFO or memory will not alter VFO 3. Examining the configuration file will show a line:

vfo 3 1 0 146520000.0 3 2 0.0 0 0 0 0 0

One need not try to decipher all the details of this line, but the vfo number is the second entry, next is a 1 corresponding to the transverter being used (in the DSP-10 there is always a "logical" transverter, even if no frequency conversion is involved). The frequency is obvious, and is in Hertz. The "3" following the frequency is the mode, FM. Entries after the 3 may vary, as they reflect the tone selections.

Adding to that example, suppose we returned to VFO 3 and used the SCRL-F7 dialog box to set a 103 Hz continuous tone (CTCSS) at a level of 90. The CTCSS is enabled by setting the tone duration in the dialog box to 9999. Now the line in the configuration file will be

vfo 3 1 0 146520000.0 3 2 103.0 9999 90 0 0

One can verify the tone is in use by the looking for the notation "103.0 90" just above the S-meter during transmit .

Still using VFO 3, let us set up an offset for our receive frequency of 146.94 and our transmit frequency 600 kHz lower at 146.34 MHz.. We will leave the setting of the tone for 103 Hz CTCSS. Using F9 and F10 plus modifiers, tune the radio to 146.94 MHz. Next we must edit the configuration file to enter the repeater offset (this will eventually be added to a dialog box).Stop the program by ALT % (DOS VISIT) or CTRL-ALT-F4 (QUIT) and edit the configuration file, UHFA.CFG. with a text editor.

Find the line in the *** VFO definitions (memch_vfo) *** section for vfo 3

vfo 3 1 0 146940000.0 3 2 103.0 9999 90 0 0

Edit this line to include a -600 kHz offset as

vfo 3 1 -600 146940000.0 3 2 103.0 9999 90 0 0

Return from the DOS visit by typing "Exit" then hit <Enter>, or restart the program. . We now have VFO 3 with a transmit frequency of 146.34 MHz,.

For a transmit frequency higher than the receive frequency, the offset will be a positive number.

Memory Operation - Most FM operation is simplified by using memories. Let us proceed to create memory number 3494 (remember this can be any number from 0 to 9999). We will leave the settings as they were in the last VFO example, including the 103 Hz tone. With VFO 3 in place, use Alt-N dialog box to create the memory. Set the memory number in the dialog box to 3494, the name to "FM34/94" and the description to "146.94 FM 103 Hz CTCSS". Obviously these three choices are arbitrary in their content. In the "check boxes" check only "Freq and Mode" and close the box. The -600 kHz repeater offset will be picked up from the VFO, even if the frequency is changed. Thus, with some planning, it is possible to borrow offset values from existing memories or VFOs. Returning to Memory 3494, this has created a text file named UM3494.MEM. The contents are:

UHFAMEM2

cur_mem 3494
mem_name |FM34/94|
mem_descr |146.94 FM 103 Hz CTCSS|
mem_incl_fr_md 1
vfo 21 1 -600 146940000.0 3 2 103.0 9999 90 0 0


Notice that the VFO entry in the memory file has taken on a special value, 21. This VFO is not available for use, except by invoking a Memory. But it can be edited in the same way as any VFO. It carries the transmit and receive frequencies, the mode, and the tone information.

Audio Filters - All audio filtering options are available in FM, including Design-a-Filter, LMS Noise Reduction and Auto-Notching.

S-Meter - In FM the power indicated is very accurate in a relative sense. It is the result of a true Root-Mean-Square (RMS) calculation of the received Signal-plus-Noise. The absolute accuracy can be good, as well, if a reference generator is available. This is adjusted by the gain factor in the transverter definition.

FM Spectral Display - In FM, the spectral display is that of the received audio. Here (but only in the FM mode) the power at the display marker is not meaningful, and so the S-meter is computed by a true RMS calculation of power in the FM bandwidth. This has a high relative accuracy and the results are shown to 0.01 dB resolution. The absolute accuracy can be good, as well, if a reference generator is available. This is adjusted by the gain factor in the transverter definition. The spectral display shows a very high level when no signal is being received. This is the FM noise that can also be heard if the squelch is set too low. When a signal is being received, the noise will be seen to drop in the spectral graph. This is a measure of FM quieting. If tones, such as CTSS are being received on a signal, these will be seen on the spectral display, and can be used to estimate the tone frequency.

The only frequency scale available for FM is 0 to 4800 Hz. The only windowing function available is "Hamming." These are automatically set with the FM mode.

Frequency Measurement - FM operation includes over-the-air frequency measurement . This is displayed in the upper left display box. The accuracy of this display is limited by the 10 MHz reference accuracy and receiver noise. If a transverter is in use, the indicated frequency will be correct, with the shift coming from the transverter definition in the configuration file. Two forms of display are always shown, the deviation from the center frequency, and the actual frequency.

FM Squelch - In the FM mode there is a number in beige between the "Mode" and "FM" on the left side. This is the squelch setting that ranges from 0 to 100, and is set by the Alt S (or Alt s) and Alt D (or Alt d) commands.

FM Transmission - This totally parallels the SSB transmission, discussed above, including PTT and microphone equalization.

HELP SCREENS
Prior to version 396, help screens come from a file, UHELP_1.TXT. This is a text file that is displayed on the DSP-10 screen when the help command (F1) is executed. With Version 396 the file name is UHELP_2. TXT. This file can be edited with most standard ASCII text editors (avoid MS Word) to customize the display. This is useful when keyboard definitions are customized, but can be used anytime.

In the text for each screen, is a number line to help you count the number of characters. This appears as

123456789012345678901234567890|23456789012345678901234567890123

There are 63 numbers corresponding to the 63 character limit. This line must remain, as is, to identify the start of each screen. Additional screens can be added by copying the "number line," followed by up to 22 lines of text. Lines longer than 63 characters, or screens of more than 22 lines will be truncated. A vertical line, "|", shows the center of the line, and is useful for setting up two columns. The number lines, of course, do not get shown as part of the help screens.

The Help File uses the 8-bit ASCII set, and allows accents. Either or both the CR (13) and LF (10) are taken as end of line. Empty lines are ignored and a blank line should include at least one space. Do not use tabs for spacing lines.

The last screen in this file should be 8 lines, or less, allowing for EME location data at the bottom. If more than 8 lines, the top of the screen showing the EME locations will be blank. This is not harmful, but also not aesthetically pleasing!

Similar instructions are included at the top of UHELP_1.TXT, and you can add additional comments there. Comments must precede the first "number line."

When the ALT-Y (or ALT-y) command has the large frequency slide rule display in place, there will also be a summary help screen permanently below the frequency dial. This has the most common commands listed. In addition, there are three more detailed screens available that occupy the entire lower-right part of the display. These are sequenced through by the F1 key. When the waterfall display is in place, the Help screens will replace the waterfall. No updating of the display will take place while the Help screens are being seen. After about 10 seconds, data will start to be be lost from the waterfall. This creates no problems for the program operation, so long as the data is not critical to the user.

Front Panels

Slide-Rule and Spectral Panels - There are two distinct "styles" available for the front panel. The default is a large size frequency readout with a slide-rule dial beneath. A help summary is always shown below the frequency dial. Alternatively, a "waterfall" type of spectral display can be shown along with a smaller frequency display. This is useful for "seeing" weak signals. All transceiver functions are available with either display style. The style is toggled by the Alt Y, or Alt y, commands as listed.

Most operating parameters are shown in the "Front Panel" display along the left side. Adjustable parameters are often shown as 0 to 100. AF Gain, mike gain and the like are exactly 1 dB per unit. Parameters that are toggled change to show their current state.

The upper right portion of the screen is a spectrum display calibrated in dB. The scale is adjustable between 10, 5, 2, and 1 dB per division. A small red cursor follows the maximum value on the display which is displayed on the front panel as "Signal Level". They are scaled by the nominal gain of a transverter and displayed as"Signal Level" in dBm. The bar graph above the Signal Level is 6 dB per bar and when all bars are lit the FFT in the DSP is going into overload. It represents the level coming from the FFT which for sine waves can be much greater than the input signal.

As the bandwidth of the spectral bins is varied, the noise bandwidth changes and, if the signal levels are adjusted to remain constant, the noise will drop as the bandwidth decreases. This is the way to operate the display if the primary interest is the signal. But if the interest is the noise, the gain should go up as the bandwidth decreases. To allow either arrangement, and any in-between, there is a .CFG variable called "knoise." If knoise is set to 0.0 the noise power will be kept constant. If knoise is set to 1.0 the signal power will be constant. Because of the noise statistics it is not always best to keep the noise power exactly constant, and for this, knoise can even take slightly negative values.

The spectrum display can be modified by Dot Selection, Scrl F5. Most people seem to prefer the connected lines.

The two bar graphs at the bottom of the screen (when diagnostics are so set by Scrl F3) represent the A/D input level and the D/A output level. These are bit-by-bit bar graphs, i.e. 6 dB/bar, and 15 bars wide showing absolute magnitude.

Waterfall Display

As of Version 396, Alt Y selection does not select the "slide rule" display. The Waterfall display is the default, and only display, for the bottom right box. If the "slide rule" display is needed, UHFA.EXE will need to be a version earlier than 396. Later DSP programs are compatible with earlier PC programs, maintaining functionality. Some features will not be available when using versions prior to V 396, such as .0014 Hz tuning.


The top-right box of the DSP-10 screen is a graphical plot of the audio spectrum, expressed as power in dB versus frequency . The lower-right box is a long-term summary of the audio spectrum, called a waterfall display. Every time the top display is updated, the lower display adds a single line at the bottom. The color of each pixel in the line depends on the amplitude of the upper display. The frequency scale is the same for the two displays. Once the waterfall gets to the bottom of the box, it automatically scrolls up 10 lines and old data at the top of the waterfall is discarded.

Several controls affect only the waterfall. Contrast and brightness determine the DB levels at which the upper display is "sliced" into colors for the waterfall. For instance, high contrast levels compress the colors into a tight cluster. When changing the controls a color bar will appear in the upper box, and can be set by experimentation. Some settings may cause the colors to move off the top or bottom of the upper box. Even though the signal and colors are above the display, they will still continue to be sliced and displayed on the waterfall. The particular colors used in the slicing can also be adjusted.

The speed at which the waterfall progresses is set by the data averaging being used (Alt-F3 and Alt-F4)

The frequency scale for the waterfall tracks that of the upper box and is generally set by Alt-J to 1200, 2400 or 4800 Hz. There are some exceptions, such as FM, LTI and EME-2 modes, where the display width is modified.

On the left side of the waterfall is the current time. This can either be hours and minutes, or minutes and seconds, as set by the configuration variable, show_secs.


Filtering

Audio Filters - There are now 8 audio filters, set by F4 and toggled on and off by F3. The default filters are:

#1 MTCH12 W8MQY matched 12WPM filter_mask= 1
#2 6CW200 200 Hz at 600 Hz filter_mask= 2
#3 6CW300 300 Hz at 600 Hz filter_mask= 4
#4 6CW450 450 Hz at 600 Hz filter_mask= 8
#5 7CW600 600 Hz at 700 Hz filter_mask= 16
#6 SSB-N 250 to 2500 Hz filter_mask= 32
#7 SSB-M 200 to 2900 Hz filter_mask= 64
#8 8CW300 300 Hz at 800 Hz filter_mask=128
(#8 is also Design-a-Filter)

There is a filter_mask variable in the UHFA.CFG configuration file . Filters 1 to 8 have values 1, 2, 4, 8, 16, 32, 64, and 128. These are added together to determine the filters that will be available.

For example, if you wanted to have filters 1, 3, 5, and 7 available, the mask would be 1+4+16+64=85.

The W8MQY matched filter is fun and useful. It is a sin(f)/f shape which is the ideal shape to maximize the S/N on a CW station. Filter #1 is set for dots at 12WPM. You must use the spectral display to tune the station exactly to 600 Hz. You can't tune by ear because it has responses on the side and the response falls off slowly. But it must be peaked, because the nose of the response is sharp and the sides must hit the side responses quite closely. When a weak signal is tuned in, it hops right out of the noise! If it is way off in code speed it won't work right either.

All of the filters use a 200 term FIR filter running at a 9600Hz sample rate, giving excellent performance.

Design-a-Filter - As described above, there are 8 audio filters, 1 to 8. The first 7 are fixed but #8 can be customized. The filters are all bandpass and require a lower and upper cutoff frequency. Filters that are narrower than achievable will not show the "asked for" bandwidth, but will represent the best that can be done.

The plot in the Design-a-Filter dialog box shows the effect of both the filter design and the receive audio equalizer.

Use the keyboard command Scrl-F4 to bring up the Filter Design box. Pick your parameters and see the results on the graph at the top of the box. After closing the dialog box, the new filter coefficients are always down-loaded to the DSP filter 8. If you are in filter 8 you get to hear it being changed! If a check mark is in the box "Use Filter on Exit" the filter selection will change to 8. If you do not hear the filter, you do not have the audio filter "on" (F3).

The effects of the "1st Sidelobe, dB" line in the Filter Design box are not obvious. Outside of the pass-band, the filter response tends to be a series of hills, or side-lobes, that diminish.. The first side-lobe can be raised or lowered in the "1st Sidelobe, dB" line. The advantage of not pushing this side-lobe unnecessarily low is a more rapid transition from the pass-band to the stop-band. Generally the parameter should be between 40 and 70 dB, but values between 0 and 99 dB are allowed.

The narrowest filter achievable depends on the sidelobe level. Roughly, a narrow bandwidth of 50 Hz wdith comes from 70 dB sidelobes, and a narrower bandwidth of about 25 Hz comes with 30 dB sidelobes. These "very narrow" filters are interesting to experiment with, but their utility is questionable!

Receiver Audio Equalizer - The equalizer is only availble with the FIL-8 selection. FIL-8 uses the 14 point graphic equalizer listed under aeqrdb in the UHFA.CFG configuration file. The frequencies are printed in a comment line below the values. Each value is for the range between adjacent frequencies, so the first value, -100 is for 0 to 200, the second value is for 200 to 400 and so on. All values are relative dB and can be anything up to +/-100 dB. Thus you can use the equalizer to add a notch band, or whatever.

Again, the plot in the Design-a-Filter dialog box shows the effect of both the receive audio equalizer, and the Design-a-Filter.

As with other portions of the UHFA.EXE program, the filter design will operate without a math co-processor. However, you will find the slowness to be very annoying!

I-F Filtering - The architecture of the DSP-10 applies DSP I-F filtering before either the FFT spectral processing or the Hilbert-transform SSB summation. This filter was originally chosen to be very conservative in removing alias signals. The results of this could be seen on the spectral display where the frequency response rolled off rapidly above 2.8 KHz. There is the option of a wider I-F filter that holds the response up to above 4 KHz. This is toggled in and out by Alt-$ (or Alt-Shift-4, if you like). The drawback is that a strong signal in the spectral display frequency range of 4.8 to 5.4 will be seen as tuning the wrong direction from 4.8 to 4.2 kHz. This is normally not a problem and the wide filter should generally be used. The I-F filter width is displayed as a 'N' or a 'W' following "Filter" in the left-hand column.

As an aside, for the technically curious, the I-F filtering is applied as a pair of low-pass filters on the I and Q outputs, following the DSP-implemented third conversion. This is totally equivalent to a band-pass filter applied before the third conversion. Audio filtering is applied after the Hilbert-transform SSB summation. Within the limitations of the Hilbert-transform accuracy, this is again equivalent to I-F filtering.

Filter Gain- As you change filters there is quite a bit going on, some of which is the gain of the filter. Narrow-band filters can have a lot of gain to sine waves at the center freq. The matched filter has a gain of 64 but the wide SSB-N filter has a gain of 1. If the filter gain is all removed, the noise can become so weak that it is lost in the least-significant bits of the DSP. When this happens, the noise sounds distorted and weak signals have harmonic distortion, all of which is unpleasant to listen to. If you have outside gain (preamp, converter) raising the receiver noise level, removing the filter gain is not a problem and the noise/weak signals sound fine. But, if you don't remove the gain, strong signals change level as you change filters, which can be annoying, and tend to cause overload problems.

So, to make this work, there is a configuration file variable called kfilt that can take values from 0.0 to 1.0. If it is 1.0 the gain to sine waves is constant. If it is 0.0 the gain varies according to the FIR filter. Starters: if you have no distortion on noise and weak signals use kfilt=1.0. If there is distortion start reducing to kfilt=0.5. It is unlikely that you would need 0.0, but... This is only available in the .CFG file.

There are 7 "fildat" entries that you will see in the .CFG file. These are a series of 9 parameters that specify filters 1 to 7. Changing these parameters will not change the filter! These are informational inputs to the PC program so that one can change the FIR filters in the DSP and then get the display to agree with the the FIR. As of now, there are only 2 parameters used, the |name| that appears just after the filter number and gain which is the last parameter. The gain is a power of two that is the inherent voltage gain of the FIR filter. Eventually, the filter response will be shown on the spectral display as a tuning aid. This provides the information to make such things work.

Table of Contents

LMS De-Noise and Auto-Notch Filtering - These adaptive filters provide either automatic peaking at the frequency of coherent signals, such as a tone, or even voice, or, alternatively a notch at any coherent signal frequency. Multiple peaks and notches are possible. If only noise is present, the automatic peaking will not find any coherent signal and will appear to suppress the noise, relative to a tone or voice signal. Thus the common nomenclature, "de-noise." Excellent background for these routines is an article in September 1996 QEX by Johan Forrer, KC7WW. This was the basis for the routines used here.

Both of these adaptive filter needs different settings, based on the signal levels. They should be used with the AGC on to both minimize this problem and to get the gain up high enough for best operation. It may be desirable to follow the LMS De-Noise by a bandpass filter (F3, F4) to reduce the high frequency singing. Try SSB-N or SSB-M along with the De-Noise.

LMS De-Noise and Auto-Notch is activated with Shift F3. You set the adaptation gain with CTRL-F3/F4. The latter is scaled 0 to 100 and if you get lost, 40 is a good starting point. Too low and it can't find a signal, too high and it oscillates.

A second adjustment is the decay rate, set by the variable denoise_decay in the UHFA.CFG configuration file . This variable controls how long the denoise waits for a signal to return after it has been found. Too high and it can built in strange ways on noise. Too low and it loses good answers after they are found, resulting in poor sound and low output. Around 90 is a good start.

The LMS De-Noise delay-line length is adjustable from the variable denoise_del_len in the configuration file . The default length is 61, (denoise_del_len=1 ) while the other option is 31 ( denoise_del_len=0 ) that may under some circumstances be superior for voice signals.

The LMS auto-null is activated by sequencing through the LMS options, OFF, DENOISE and AUTONOTCH with SHIFT-F3. The adaptation gain is adjustable by using the same adjustments as for the Denoiser (CTRL F3 and CTRL F4). Higher numbers are more aggressive autonotching. At 0 it does nothing and by 30 to 50 it should get most any collection of steady, clear tones. It can't find coherence in rough or noisy tones and doesn't do well on those (this is why a voice can almost completely make it's way through). Be careful about accidentally leaving the notch on while on CW!.

By the way, LMS stands for Least Mean Squares and is the name of the algorithm used, a part of 'Adaptive Filters.'

LMS denoise/notch and the audio filter can run simultaneously. Play with combinations if you want.

Table of Contents

AGC and RF Gain- The AGC is audio derived and has fast-attack and slow-release. The release time is adjusted by Scrl G and Scrl H. A setting of 0 turns the AGC off and drops the no-signal gain by 48 dB. This needs to be made up for by an increase in the AF Gain. The 48 dB of AGC range is about all that is useful for the dynamic range of the AD1847 A/D. This all takes place within the DSP.

External to the DSP is the RF Gain control that allows about 36 dB of additional dynamic range. At full 100 RF Gain, overload of the receiver takes place at an input level of about -55 dBm which is about 400 microvolts. Although this is a very strong signal, if there are local stations nearby, problems may occur. The manual RF gain reduces the RF gain by about 36 dB, raising the maximum input to about -19 dBm or about 25,000 microvolts. Unfortunately, this also reduces the receiver sensitivity, so it is normally best to run with full RF gain.

The overload characteristics depend on the frequency of the strong station. The A/D converter only "sees" a strong station if it is within about 10 Khz of the indicated frequency. Outside that range, the dynamic range is limited by, cross-modulation, intermodulation, and blocking. These effects require quite a bit more interferring signal level than overloading the A/D converter.

Starting with ver 396 of UHFA.EXE, there is the ability to change the RF gain using PAGE UP, a single, unmodified key. This is useful when multiple stations are engaged in net style operations or situations where one station overloads the ADC, and the operator would like to copy the station causing the overload. This works by changing the gain by a in multiples of the 6 db gain steps. Available steps are 6, 12, 18, 24, 30 and 36, corresponding to 1 - 6. The step can be modified in the configuration file, UHFA.CFG in the entry rfgain_toggle.
Binaural Audio- This is a simple function that does a lot. Read Rick Campbell, KK7B's article in March 1999 QST. He creates the binaural sound by getting independent noise and correlated signals from I and Q channels. The DSP-10 binaural audio works by delaying the sound for the right ear. With sufficient delay the noise going to the two ears becomes independent. The signal, depending on it's frequency stays fixed in position and your mind does the rest, just like in everyday life. Try it. It is great for CW and on voice it sounds like you are in the room with the other station. Preliminary results indicate that it improves sensitivity on weak signals. It certainly reduces fatigue. More information is also available in the ARRL book Experimental Methods in RF Design (Chapters 9 &11).

You may find that the effect is not as pronounced if the audio bandwidth is too narrow. Experiment to see what works for you.

The binaural audio is toggled on and off by ALT-E keyboard commands. The amount of delay is adjustable is powers of two, by the configuration file variable delay_right . The default is 1024 set by a value of 9 in CFG. Values of 1 to 10 are allowable with 1 being 4 delay units, 2 being 8 delay uits, up to 10 which is 2048 delay units.. Each delay unit is 1/48000 sec, or 20.8 microseconds, so the default delay is 1024x20.8 microseconds=21.3 milliseconds.

Moon Information -
Automatic EME Doppler corrections for the receiver are available with ALL modes except FM, even SSB. This correction is done with high accuracy to support the weak-signal modes of chapter 2. A by-product of the high Doppler accuracy is excellent data for azimuth and elevation. The data is displayed as a SCRL-F3 option. Azimuth, elevation, Doppler shift, and relative signal level are displayed.

To make the Moon Doppler calculation possible, it is necessary to know the latitude and longitude of your station and the other-end station (that can be your station again, for self echoes.)Your station is referred to as 'loc 0' and is always part of the EME path for Doppler as well as the location for az and el calculations. There can be up to 9 more locations that are used for the second half of the Doppler calculation. All locations may be entered from a Dialog Box opened by CTRL U.

All 10 'loc i' may be still entered through the UHFA.CFG file. The format is shown as a comment in the file. Each line looks like

loc 0 |W7XYZ| |W7XYZ's location| 44.123 -123.567

where the vertical bars delimit strings. Put 2 spaces outside the vertical bars. The first string is 6 characters, or less, and uses in the Moon display line. The second string is up to 31 characters and allows more detail about the location. The latitude and longitude are in decimal degrees. If your GPS gives you degrees and minutes, use your calculator to divide the minutes by 60 and add onto the degrees. West longitude must have a leading minus sign.

There can be anywhere from 0 to 10 locations. They can be in any positions and if they have not been entered in the UHFA.CFG file they are skipped over by the '<' and ' > ' commands.

All loc's can be seen in detail in a table on the last Help screen (F1.)

EME Doppler Corrections - Receive frequency correction for EME (MoonBounce) Doppler is available for CW and SSB (as well as the weak-signal modes LHL-7 PUA43, EME-2 and LTI that are detailed elesewhere). The correction can be toggled on and off by ALT L, or ALT l. It is in effect only when an EME path is being displayed on the bottom line. An 'E' below the frequency readout means the feature is enabled. If a receiver frequency is displayed to the left of the 'E", then the correction is being used. There are situations when the 'E' will show in beige, but the frequency is not displayed and corrections are not being made. An example of this is the FM mode. When the Doppler correction is being made, CW and SSB stations will be received as though no Doppler shift existed. For example, if the other station is transmitting USB on 144.085 000 MHz and the Doppler shift is 234 Hz, the Transmit Frequency box can be set to 144.085000 and the station will be tuned in. The receive frequency will show as "144.085 234 E."

Note that the PC clock needs to be set closely to have the correct EME-Doppler correction. At 2-meters an error of 1 minute can create a 1 Hz error. At 1296 MHz, this will be 9 times greater. Software clock corrections can be applied to correct the clock as is explained below for the "PUA43 Mode." But, in general, it is best if the PC clock is maintained within a few seconds of UT/Local Time.

Sun Noise - To aid in Sun noise measurements, the az-el coordinates of the Sun are displayed (Scrl F3.) The dB number is the slight variation in Sun distance that occurs over the year (Sun distance^2.) For the Sun, the location of the az-el coordinates can be changed to all 10 loc's. Also with this VERSION we have the P2T which eases the peaking and measurement of Sun noise.
Power Measurements - There are three different power measurements displayed.

When in any of the active diagnostic modes (Scrl F3,) there is a dB number in the very lower-right corner. This is the average power of the spectral display, converted to dB. This is appropriate for Sun/Earth noise measurements, as long as no signals are present.

The ' Signal Level ' displayed on the left, under the S-Meter bar graph, is the spectral level at the highest point (the little red marker.) This marker is the highest amplitude level at frequencies above 200 Hz. This avoids being captured by 60 or 180 Hz pickup noise.

Finally, the rms value of the input signal is calculated in the DSP and is displayed below the S-Meter when the mode is FM. This is a specialized measurement that can be used for signal plus noise measurements.

In the DSP the average power is computed over the entire 12 kHz bandwidth used for FM. This is done 48,000 times a second. After converting to dB this is sent to the PC for display. The relative accuracy of this power computation and logging is better than the 0.01 dB that is displayed, making it very suitable for Sun noise measurements. This is also more accurate than the spectral average power levels that are shown in the lower-right corner in diagnostic modes 1 and 2.

Data Record - The logged power data after non-coherent integration can be saved directly to disk. This is toggled on and off by the Alt F command. It is saved to a file called UHFA1.DAT and if the file exists, it is appended to the end of the existing data. The data is time and date stamped for future use. It is not compacted, though and can produce some big files. To reduce the file size increase the non-coherent integration (Alt F4). The beginnings of a companion program EDFILE01.C and EDFILE01.EXE is available. It reads the data file and replays the data allowing additional smoothing as well as Doppler slope correction and various other feaures. EDFILE is not documented except through the C listing, but the program listing comments do much to describe the operation.

LTI , PUA43 , and EME-2 weak-signal modes also have data saving from the ALT-B menu respectively.

Screen Saves - Sixteen color snapshots of the entire screen including the spectral displays can be taken and stored as .GIF files. These can be printed or edited with graphics printing programs, or handled with your Web Browser. The GIF file is given a file name Uoddhhmm.GIF where o is the month as a single hex character (1,C), dd is the day (1,31), and hhmm is the time. The default leading character 'U' can be altered from the UHFA.CFG configuration file by the single character for the variable file_ident. Note that the same variable sets the leading file name character for all data output files. For example, to set the leading character to 'H', the configuration file should contain the line

file_ident |H|

There are two spaces preceeding the vertical bar.

Automatic Screen Saves - Screen saves can be done automatically on a periodic basis. The configuration variable, scsave defaults to 0, but if it is set to a value greater than zero, it becomes the number of minutes between saves. One should use this with care or be prepared to see many screen save files! To produce an automatic screen save every 10 minutes, place the following line in the configuration file:

scsave 10

The maximum value for the interval is 1439 and the count resets at midnight. These automatic screen saves are at the top of the minute.

The directory for screen saves defaults to the same directory thatcontains UHFA.EXE. This can be changed by the configuration file variable fscreen_path. Leaving this variable blank continues to use the default directory. If one wanted to use the A drive, the following line should be in the configuration file:

fscreen_path |A:\|

As with all string variables, there are two spaces ahead of the first vertical bar.

ON-SCREEN COMMENTS - When (ALT-G) Screen save is entered, a modal dialog box appears in the lower right corner of the waterfall area. This allows two lines of comments of 24 characters each. Enter text and use the scroll up and down arrows or backspace as needed. When the box is ended with an ENTER, the box is redrawn at minimal size and the screen save continues, including the comments. Then they are cleared and the missing screen replaced. If no comment is needed, just hit ENTER (with no comment entered) and the box disappears and the screen is saved. Default is to have the comment box open with screen save ALT-G and can be changed to disable this action by changing "use_scs_box 1" to "use_scs_box 0"

Auto-Display - Shown as AutDisp on the left side of the front panel screen, this is toggled on and off by the ALT-C keyboard command . The purpose of this function is to keep the spectral display at the same average height, even though the receive gain may have changed with temperature or other factors. This is important when dealing with weak signals and the display is in 1 or 2 dB/div. For ordinary operation the AutoDisp should be Off. Otherwise, the noise level appears to go down every time a strong signal is tuned in note that AutoDisp stops the display of the average spectral level that can be seen in the lower-right corner with diagnostics mode 1 or 2. This is the value that is kept constant!

Shut Down - If you use the Scrl-Alt-F4 command to quit to DOS you will not only feel like it was more orderly than using the power switch, but you also update the configuration file. This will cause the transceiver to start with the last used parameters when you start up next time. This assumes that you have not added a line of "quit_save_state=0" to the configuration file.

Bottom Data Line - The Scrl F3 changes the bottom. There are seven different data lines that are sequenced through:

0 No data, but index lines that line up with upper screen frequency ticks.
1 DSP status byte dump
2 A/D and D/A level bar graphs
3 Moon data
4 Sun data.
5 time data
6 latitude, longitude, height and grid square, derived from the GPS data.


The DSP status line is not easy to read. It consists of the 19 status bytes, printed in hex, (0 to 9, A to F), followed by a letter idicating transmit or receive, the current UHFA.EXE version and on the right a dB value that is the relative power in the last white trace. For many purposes, there are only a few items of interest. The first byte is the versin number for the DSP software, UHF3.EXE. As of February 2003, the only values that support the PC software are 20 and 21, corresponding to DSP software versions 2.0 and 2.1. Just past the 'R' (or 'T') is the PC software version. This should be a number, such as 3.00.

The A/D and D/A levels represent the highest value seen by these data converters that are on the EZKit Lite.There are 15 bars that start whte on the left, progress through green and end with 6 red bars on the right (these are the default colors---others may be set in the configuration file ). These bars represent the magnitude of the 16 bit data converters, requiring only 15 bars since the sign bit is not involved. Each bar represents a 6 dB increase in level above its neighbor to the left.When all bars are in use, the data converter is either about to overload, or is doing so. It is normal for several white bars of the A/D level to be in use, even if no input exists. This represents the A/D noise that restricts the dynamic range of the converter.

Cursor Keys for Tuning and Audio level - Here is a neat one, the W7SZ cursor keys. This thing is so convenient, I am really not sure that one needs a knob!! These are the cursor keys at the lower right of the keyboard:

Left Arrow Frequency down a little
Shift Left Arrow Frequency down quite a bit
Right Arrow Frequency up a little
Shift Right Arrow Frequency up quite a bit
Down Arrow AF Gain down a little
Shift Down Arrow AF Gain down quite a bit
Up Arrow AF Gain up a little
Shift Up Arrow AF Gain up quite a bit
Page Down AF Mute toggles on and off

As can be seen, the shift key changes the amount. I like 50 Hz and 1 kHz for frequency and 2 dB and 10 dB for AF Gain. These are defaults, but are set in the UHFA.CFG file by delf, delf_sh, deldb, deldb_sh . The values can be negative in which case the <- become freq up. For instance, if you wanted to change the cursor tuning (without shift) to 25 Hz, alter the configuration file line for delf to delf 25

Tuning with milli Hertz Resolution

With version 396 additional tuning steps of .0014 Hz are available .
Version 3.96 expands on this, adding additional keyboard entry for steps of 1, 10 and 100 milliHz. These tuning steps are available when the frequency display box is displaying nine places past the decimal.  The direct frequency entry box, ALT 9 can also be used to enter the frequency directly while the display is in milliHz tuning mode. Use Scroll Lock plus Z (<SCRL><Z>) to toggle tuning resolution.

   milliHz tuning steps enabled

The UHFA.CFG file can be edited to use the delf, delf_sh, (left and right cursor) to assign these frequency steps to the cursor keys, as below.

//*** Keyboard definitions (memch_kbd) ***
//
delf .010
delf_sh 2.000

Note that all of the above require the milliHz  tuning to be enabled. If the cursor keys are assigned to less than 1 hz steps,they are not active when milliHz tuning is off. This is a possibilty, not a recommendation.

  milliHz tuning steps disabled

S-Meter - The S-meter bars are tied directly to the dBm number under them. S1 to S9 are exactly 6 dB each and the bars over S9 are 10 dB each. In addition the S-meter numbers and bar graph now work for signals that are off-screen on the upper spectral display. To make this happen, there is a change in the mode of operation at about -100 dBm input. Below that level the signal strength comes from the spectral data, indicating the peak on the upper spectral display that is marked with a red circle. At higher levels, an RMS (power) calculation in the signal band (from the DSP) is used. The transition is indicated by a 'P' showing to the right of the strength number, meaning that a power measurement is being used. Including the RF gain, this gives an input range from about -150 to -25 dBm that is displayed correctly. If one is using the Signal Level display to make comparative measurements, it is desirable to avoid switching between the two methods of measurement.


Time Marks - The time marks on the waterfall can show either mm:ss(default) or hhmm. The hour and day can often come from the lower left corner. The use of mm:ss allows you to identify a time in the waterfall to the second. If you want to use hhmm, change the variable show_secs in the .CFG file to 0.

Mode Mask - This is a UHFA.CFG configuration file variable that allows the operator to ignore transmission modes that are not of interest. It is the sum of the values for each mode desired. The values are listed below, and also in a comment in the .CFG file, just above "mode_mask x." As an example, if one wanted to only have CW=1 and USB=2 available, they would set mode_mask=3. In order to not allow a modeless radio, the CW mode is always available.

CW mode_mask= 1
USB mode_mask= 2
LSB mode_mask= 4
FM mode_mask= 8
LHL7 mode_mask= 16   removed in Version 394
PUA43 mode_mask= 32
EME2 mode_mask= 64
LTI mode_mask=128

Last Key Hit - If you ever wondered what key you hit, it now shows in the lower left, if the keystroke had any effect. It shows the function of the key, abbreviated to 6 characters. This also lets you find out how things work by hitting keys experimentally!

Out-of-Lock - This hardware feature indicates if either of the phase-locked loops is not locked. Running your frequency up and down and watching the error message shows the lock limits. Mine showed 143.35 to 148.8.

Vertical Cursors Flag Posts, and Goal Posts - Provision is made for placing fixed cursors on the screen for lining up the received signals on the upper and lower spectral displays. These are available in various modes, where they make sense:

MODE SINGLE CURSOR DOUBLE CURSOR
CW CW Offset Frequency None
LTI Center Frequency Low and High from ALT-B Box
EME2 Center Frequency Band Edges from ALT-A Data
LHL7 Times-2 Frequency End of Character & Times-5
PUA43 CW ID Frequency Band Edges


The Single and Double cursors are turned on by the CTRL-A and CTRL-D keys. They are turned off by hitting any key, except ALT-G; that will do a Screen Save with the cursors still showing. At the bottomline of the screen, the frequency of the Vertical cursors is shown, in Hz.

Audio Processor - All of the the regular functions are available without RF hardware, using the DSP-10 audio processor .

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