TADX - RECEIVERS - OPERATING THE PERSEUS SDR RECEIVER

There are many functions within the BW pane:

a - Double left click to centre the signal carrier
b - Left drag to fine tune the signal
c - Rotate the wheel to adjust the selectivity filter bandwidth
d - Drag the two filter edges independently
e - Tune via the "wheel step" arrows
f - Right drag to emulate passband tuning

a) DOUBLE LEFT CLICK: Double click on the waveform in the BW pane, to centre the carrier.

b) LEFT MOUSE CLICK AND DRAG: Left click, hold and drag within this window, to drag the frequency around, in a "fine tuning" mode.

c) BANDWIDTH: The bandwidth is continually variable from 25kHz to virtually zero on the PERSEUS. The buttons may give the impression of fixed bandwidth, with settings of 25, 12, 6, 3, 1.6 and 0.8kHz. This is not so however. Hover the mouse over the shaded area within the BW pane, and turn the mouse wheel. The selected area which is shaded will be seen to be continually variable. If very narrow bandwidth is required, choose a lower selection, like 1.6, or 0.8, and it is possible to reduce the bandwidth to virtually zero. Using a lower setting not only "magnifies" the screen, but also switches in different filters.

d) DRAG THE FILTER EDGES INDEPENDENTLY: Left mouse click, hold and drag to "grab" the edges of the shaded area independently of each other, to manually increase or decrease the bandwidth. A small arrow appears on the red line when this adjustment is being made. This can be useful for example if there is an interfering signal on one of the sidebands only.

e) TUNE VIA "WHEEL STEP ARROWS": The white arrows either side of the tune notch and PBT buttons act as a tuner up and down in the steps assigned by the "wheel step" function.

f) PASSBAND TUNING: PERSEUS has a right click function within the BW pane, which moves the whole selected part of the window around. Right click and hold the shaded area, to drag left or right. This is the SDR emulation of Passband Tuning, as there is no real PBT in a zero IF single conversion receiver like Perseus.

In the example below, PERSEUS is tuned to 1070kHz, Canadian MW station CBC Moncton. There is QRM from 1071kHz from UK Talk Sport. If the emulated Pass Band Tuning is used, the shaded filter area is right clicked, held and dragged to the left, away from the carrier of Talk Sport. CBC is then heard free of interference.

The freq centred on 1070 (left), but using PBT the QRM vanishes (right)

NOTCH FILTER: Introduced since version 1.0, this function can "notch" out a selected carrier, or area of spectrum close by the desired signal. The above PBT example worked well with CBC 1070, and the Euros on 1071. But excellent example of the notch filters use is as follows. Again a MW example. Until early 2008, many dxers noticed an unidentified carrier on around 1181kHz. If a European Dxer wishes to listen to WHAM 1180 from Rochester, NY, the PBT as per the example above could be used to drag the filter hf to get rid of the Euros on 1179. But what of the unidentified carrier hf of the desired signal. The notch filter can completely eliminate this unwanted menace.

6) MAIN SPECT/ WATERFALL WINDOW:

The main Waterfall / Spect window allows operation of many functions associated with direct tuning.

MOUSE OVER & WHEEL STEP: The centre of the SDR Receiver is the Spectrum / Waterfall screen (which ever mode the user chooses). Hover the mouse over anywhere within the main Spect / WFall window, and turn the mouse wheel. This will step the receiver up or down by the amount defined in the "wheel step" pane. The options are 25, 12.5, 10, 9 and 5kHz, as well as 100hz and 1hz!

Common examples for dxers include 9kHz steps for dxing European MW stations, or 10kHz for The Americas. The 5kHz step is ideal for SW/ HF broadcast band dxing.

NB: This is a very convenient method of zipping up and down the band for both MW dxers (steps of 9 or 10kHz), and SW dxers (in 5kHz steps).

DIRECT CLICK: Double click directly onto a wave or waterfall line and the receiver will jump straight to the frequency selected, to the nearest full 1kHz (no decimal places).

DIAL POINTER: PERSEUS has a dial pointer which spans the main Spect/ Waterfall window vertically on the frequency to which the receiver is tuned. The user can left click, hold and drag the "dial pointer" to change frequency, but only as long as the "CENTER" button in inactive. This is another way to move up and down the frequency spectrum quickly.

Dial pointer in waterfall mode in conjunction with the settings in BW pane

The pointer is present on the Spect view, and on "mouse over the tuned frequency" in the waterfall mode. A waterfall screen with a 400kHz span does not really show up the pointer very brightly against a background of multiple carriers. The pointer is more obvious on low "SPAN" settings in the waterfall mode. The pointer changes in conjunction with adjustments made in the BW pane, and is physically as wide as the selected bandwidth, as seen within the BW PANE.

TUNING: Center button - active: This button keeps the tuning dial pointer in the centre of the frequency scale. If a waterfall line is double clicked when the Center button is active, the frequency scale moves along, and the whole waterfall will move along. (The user may lose track of which waterfall line is which, till the screen catches up) If the "center" function is activated, the "tuning pointer" will not move from the centre of the screen.

"Center" button inactive

TUNING: Center button - inactive: The user can click anywhere on the waterfall, or spectral screen, and the receiver jumps to the new frequency without moving the whole waveform/ waterfall. The pointer will also move, and can be dragged across the frequency spectrum.

There are various functions related to the main window other than direct tuning, see above.

SPAN could also be described as increasing the magnification on the Spec/ Waterfall screen. This function can be used on playback as well as live listening. SPAN is directly related to the sampling rate setting. The waterfall can not show 400kHz if for example the receiver is only sampling 250kHz at the time. (Or is playing back a recording of 200kHz of spectrum)

WATERFALL SPEED: The scroll bar to the right of the waterfall pane slows/ speeds up the waterfall.

MARKER: A right mouse click feature is available within the spect/ waterfall pane. Right click on up to four frequencies, and a small arrow appears. In waterfall mode, the arrow is situated where the signal waveform would be on the spect view. On the spect view, the arrows are situated where the mouse was right clicked. The screenshot below shows the numbered arrows, relating to Mkr1-Mkr4 in small text on the top right. The frequency and signal in dBm is also given.

RECORDING / PLAYBACK

According to an on line poll, the biggest attraction to PERSEUS is the record feature. Technology has advanced enough to enable the PERSEUS SDR to record a massive 1600kHz of the RF spectrum, and play back the file at a convenient time, with all the desired features of the receiver still available to optimise reception, eg bandwidth, mode, passband tuning, etc. This spectrum record function has particular interest to DXers whose main focus is MW or Tropical Bands, though not of course exclusively. (The receiver has even been tested as a BAT DETECTOR!!)

Perseus can record a spectrum bandwidth of 1600, 800, 400, 200, or 100 kHz. This is selected from the SAMPLING RATE buttons. These are marked 2000, 1000, 500, 250, and 125, which is the amount of spectrum the receiver is sampling per second. These figures may seem slightly misleading, as the Perseus will playback slightly less than the sampling rate.

These playback values are as follows:

1600kHz at 2000kHz sampling rate
800kHz at 1000kHz sampling rate
400kHz at 500kHz sampling rate
200kHz at 250kHz sampling rate
100kHz at 125kHz sampling rate

Sampling rate pane

The PERSEUS will record up to a maximum of 10 minutes, before automatically creating a new (.wav) file. After 10m a new file is created with the same name "plus 1". 080117_2308.wav file is the example below. The next file becomes 080117_2309.wav. The file size of an automatic 10m recording is around 1.757GB at 400kHz, 878MB at 200kHz, and 439MB at 100kHz of spectrum recorded.

STOP, PLAY and RECORD buttons, and PROGRESS BAR at the bottom

RECORDING:

To record from the PERSEUS, select the chosen frequency limits required in the main window, by dragging the frequency bar. Click on the record button, which is third from the left at the bottom of the screen. A new window pops up asking for a user defined file name and folder location to store the file (see below). As seen in the example above, the file may be named to include the date and time, for ease of finding. The example above is called 080117_2308, meaning the file was recorded on January 17th 2008, at 2308UTC. The PERSEUS takes the file time from the computer clock, so it is a must that the PC clock be kept accurate. The software also displays how much free space is left on the hard drive. In the case above, 371.14 GBytes are free.

File name and location window pops up on pressing RECORD

NB: While recording, it is NOT possible to tune around beyond the frequency limits of the spectrum being recorded, eg the user can not check a SW frequency while recording say 560 - 960kHz. The same of course stands for playback. It is not possible to tune beyond the recorded frequencies.

PLAYBACK:

To play back a file which has been recorded at an earlier time, click on the "Wav" button, within the "INPUT SELECT" pane. The PERSEUS stops receiving live signals and the "Wav" and "File" buttons are now activated. Click "File" and browse on the PC to the location of the pre recorded file(s). Then simply press the PLAY button. These buttons are similar to those found on most domestic DVD players and video recorders.

If the receiver has created numerous automatically named files, PERSEUS will playback the whole series of files if required. This playback should be continuous and flawless, even during track/ file change. The PERSEUS software will playback .wav files which have been copied to a DVD equally as flawlessly.

The input select pane

During playback, the Perseus software will display date and time in the same format as during recording. Therefore so long as the PC clock has been kept accurate during recording, so too will the playback time.

A PC clock sometimes becomes wildly out of time, especially in the mid winter cold of a radio shack. This also means that windows automated file date of creation will be wrong. A replacement back up battery on the PC motherboard may be required if the clock goes off time frequently.

NB: Playback is restricted to the PERSEUS hardware being connected and running on the PC. The software will not activate if the PERSEUS is not connected to the PC.

MOVING FORWARD AND BACK DURING PLAYBACK:

Since software version 1.0, single left click anywhere on the progress bar to advance to a chosen point of the recording.

To loop the playback over a smaller selection, simply left click and hold at the desired spot on the progress bar. Drag the mouse pointer along to the right to create a new line, which will be a much paler shade of yellow, almost see through. Let the mouse button go, and playback immediately begins from the new desired spot. This should be flawless and instant. The player will repeat the new selected section only over and over until stopped. This may be useful if the user wishes to repeat a possible station ID over and over again.

A left click on the line cancels the new selection, and returns the playback to the beginning of the file.

NB: The progress bar differs slightly in operation from common progress bars in WINAMP, or WINDOWS MEDIA PLAYER for example.

TROUBLESHOOTING: If the user fails to create a new line, but only "clicks" to attempt to advance playback by a few minutes, the software may seem to "stick". The player is probably only playing back a very small selected area over and over again, and hence the impression of "stuttering and jamming".

The light yellow line to the right just before the mouse button is let go. Once released, the deep yellow line jumps to the new place on the progress bar, and immediately begins playback from the new point.

THE OTHER CONTROLS

A detailed description of the other controls on the software control panel, beginning at the top left of the screen:

ATT: Like on a conventional receiver, the attenuator reduces signal input. This may be useful if a user has problems with strong local signals appearing on frequencies other than their own. eg from a local radio ham, or local MW station. Relays are heard clicking in the PERSEUS unit when the attenuator is switched in and out.

FRONT END: Presel Preamp and Dither: Under normal conditions, these functions may seem to make little difference. There are however, situations in which their use becomes apparent.

"Presel" (which inserts the receiver preselection filters) is very useful when very strong out of band interfering signals may saturate the A/D converter. Eg, if the user is tuned to MW, while a radio amateur very close by is active on 160 or 80metres, and breaking through. Switch in the Preselector in this instance to prevent or reduce overloading.

"Preamp" is less noticeable as it varies the receiver sensitivity just slightly, no more than 2/3 dB. It may be difficult to notice any real difference when broadcast listening signals are very strong, and atmospheric noise is far beyond the receiver's own noise level.

"Dither" reduces spurious signals. Spurious responses are improved at the expense of the receiver sensitivity (only a couple of dBs). Users may have this function "always on" unless tuned for example to a very quiet 10m band.

Top left of Perseus

AMPLITUDE: Both "ref level" and "scale" alter the height and position of the dancing waveform in the Spectral wave mode on the main panel as well as the waveform in the secondary “bandwidth” window.

FREQUENCY: Frequency display, as on conventional receivers.

MODE: The reception mode buttons (AM, SYNC AM, CW, RTTY, USB, LSB, FM, DRM, USER) are placed along the centre of the screen.

USER DEMODULATOR: When the user demodulator is selected the VAC (Virtual Audio Cable) output is fed with zero-IF IQ samples, filtered with the selected bandwidth and normalized in amplitude with the selected AGC setting. This mode is useful when a third party application wishes to process the zero-IF data stream at the selected frequency.

Cal and Clr: An example of how to calibrate the PERSEUS SDR.

a. Tune to a WWV signal at 10 MHz.

b. Select "Center" in the "Tuning" control window,

c. Select the 0.8kHz filter in the "BW" window,

d. Double click the WWV carrier in the Secondary Spectrum Window to exactly centre it at a 0 Hz offset (before double clicking it will appear at some offset from the center due to the finite precision of the Perseus reference oscillator).

e. Click "Cal" on the "Tuning" control panel. In the case the calibration has to be repeated, click CalClr and repeat the above procedure. With some experience you can calibrate the clock with a precision which is much higher than the clock stability itself.

VOLUME: Volume control is on the bottom right of the software, though many users prefer to use the volume on their external amplifiers.

NR: NR control activated since version 1.0 will reduce background noise dramatically. The noise reduction dsp block can be operated in all modes except with DRM and USER demodulators.

SIGNAL METER: The S meter is marked in both S points and dBm. The S meter is accurate to within .2 or .3 dB across the range.

When operating in Sync AM mode (SAM), a small "LOCK" display appears in the top right of the meter, when the demodulator locks on to the AM carrier.

ADC CLIP: A red ADC clip mark appeard in the S meter, which means that it is necessary to switch on the attenuator. This is a warning comparable with audio VU-meters on old tape recorders. You will notice distortion when staying in un-attenuated mode.

AGC: The Automatic Gain Control settings are fast, med, slow and off. Slow works well on strong SSB while listening for example to "top band".

MEM box: There are three function buttons associated with the MEM BOX; "HFCC" "EIBI" & "USER". The PERSEUS operating software displays information from the "HFCC" and "EIBI" on line frequency databases. So long as the text files are composed in the same format as the HFCC database, the user can produce his own personal database. The user database file should be named "userlist.txt", and kept within the PERSEUS folder.

As seen in the example above, when a frequency listed in the database is tuned, the entries are displayed in the MEM window. Station names appear if the tuning frequency is within +/- 500 Hz of the frequency listed in the database. Stations scheduled at 1200UTC for example, do not show in the MEM window at 2100UTC. Time & even day of the week of stations appearing in the window match time and day displayed by the PC clock.

HFCC (High Frequency Co-Ordination Conference) database. PERSEUS software requires 3 files:

1) hfcc.txt
2) broadcas.txt (not a misprint, this is the file name, kept to 8 characters)
3) site.txt

The main database download is called something like "B07ALL00.TXT". This is the file which has to be renamed to "hfcc.txt"

EIBI database file will be named something like bc-b07.txt by default and should be renamed "eibi.txt"

Text files within the PERSEUS folder:

1) hfcc.txt
2) broadcas.txt
3) site.txt
4) eibi.txt
5) userlist.txt (only if a user file is required)

NB: Names of any updated text files should be changed and copied into the "PERSEUS" folder, where the operating software is stored. Allow the old files to be overwritten. If the file names are left as original, the operating software will not recognise them.

If the user tries to rename the database file to "eibi.txt" without knowing his file extensions within windows are hidden, the real file name may even end up as "eibi.txt.txt" which PERSEUS will certainly NOT recognise.

After PERSEUS drivers are installed, and the PERSEUS software is running smoothly, some users may wish to experiment with the WINRAD interface. WINRAD is a software application developed by Alberto di Bene, I2PHD, and is available from the following web address: http://www.winrad.org/winrad/

RUNNING PERSEUS through WINRAD:

1) Install the latest WINRAD software, available from the WINRAD web site. This exe file does install files on to the PC hard drive. It is a small programme, eg Winrad_130b13_setupXP.exe is only 1.411KB.

2) Copy all the files contained in the folder “WINRAD” from the PERSEUS installation CD, to the directory where Winrad has been installed (usually C:\Program Files\Winrad). The files are also available on the WINRAD web site as a download for PERSEUS users, and in the microtelecom web site..

The 6 files are:

ExtIO_perseus.dll
perseus125k24v11.sbs
perseus250k24v11.sbs
perseus500k24v11.sbs
perseus1m24v11.sbs
perseususb.dll

3) Start Winrad, open the “Show Options” menu, click on “Select Input” and choose “Perseus HF Receiver”.

4) Click the START button on the WINRAD software to run PERSEUS through the WINRAD software.

NB: The WINRAD software will play back a .wav file recorded by the PERSEUS, and allow the full 500kHz sample rate to be tuned. On playback there are an extra 50kHz either end of the original PERSEUS frequency span of 400kHz, although reception in "the outer limits" can not be guaranteed to be free from unwanted signals.

WINRAD will also play back PERSEUS .wav files without the need for the SDR being connected to the PC.

All specification are measured at 14.15 MHz, with Preselector ON and Preamp OFF, unless otherwise indicated.

Microtelecom s.r.l. declares that the Perseus receiver complies with the European Community EMC standards: