Friday, January 25, 2008



PERSEUS SDR-RECEIVER – A Pretty Excellent Receiver of Software … OR – A Poor Example of Receivers … - First Impressions (by TK)

These impressions are something found during a brief test arrangements on January 21-22 with a Perseus + Table-top PC Fujitsu-Siemens (about 1.8 GHz – 1 Mb mem. + 250 GB HD). The rx was compared mostly to a SDR-14 & IQ + a communications receiver Icom R9000.

Generally the look and feel is great with this equipment and the installation of the software was a piece of cake. The software (beta 0.31) was distributed on a CD with the receiver. There were a HF-Span software (showing 0-40 MHz span) and drivers + dll´s for the WinRad, too. It was very easy to calibrate the set using just the mouse to move the scale and the “CAL” button on the screen. As can be seen at fig.1 the user interface is nice and that can even be improved the Griffin PowerMate knob. There are normal demodulations like AM & SSB, but also syncro-AM (SAM) which is very good, locking easily (the freqyency readout does not change however). In addition you can demodulate DRM using the Virtual Sound Card driver (you have to be the latest version 4.8 for that) and the Dream-software. The screen having two windows is good so you can have a larger view up to 500 kHz and the demodulation window with if-bandwith etc on another smaller screen. It sounds also that the noise blanker works good for sudden impulses (like electric fences) whereas that of the SDR-IQ is useless. However I have not personally tested it largely as my local horseowner has switched the fence off!

On the screen you can set frequency also by clicking the arrows below the small secondary window. This is handy, when operating with a laptop without mouse. The averaging system in the software is done nicely on the screen – you can adjust it manually by clicking and dragging the vertical sliders both for the main and the second window. On the screen you can use also the memo (memory tables) where you can load lists of potential stations and there are already memos of EiBI list and HFCC-tables included. You can import your own list to the memo table as well. Software worked OK although there are some problems still with the listening to the recorded (captured) RF-file. While checking how many stations you can have on one frequency (if there is a vertical scroll) I found that you can but up to six on the channel - so a scroll should be good if you wish put lists like "potential NA / TA -stations" etc - these lists have usually dozens of stations on each channel.

You have to use the transformer (5 V) which comes together with the rx and I have seen reports that this unit (a switching transformer) does produce some noise especially to other RXs (using splitters), but I did not note very much interference in my set-up. However I have already some noise from other PC-equipments, mainly from my LCD-screen which I have to switch off when doing serious RF-recording at daytime with low signal levels.

Sensitivity & Strong signal handling seems to be adequate - I would say the sensitivity is a bit worse than that of the Icom-receiver (R9000) and I have seen some figures at about 2 uV (10 dB/SN, AM-mode); however, when used with active splitter (with 10 dB gain) and/or amp. of 10 dB with a LW of 150 m or BOG 300 m the rx did overload and I had to set the attn to -10 dB on the program. But this is what is happening with other sdrs (14 / IQ and WinR) as well. That is never a problem with my old Icom, AOR or EKD 515 (DDR-rx).

Frequency measurements are a bit harder to do with the Perseus (compared to IQ using Spectravue) basically as the minimum SPAN in receiving is 1.6 kHz (showing also the max. BW resolution 1.9 Hz). As can be seen at the picture, you have to “click” the markers on screen (you have to use as good resolution as possible) whereas Spectravue with 14/IQ gives you automatically the 4 strongest carriers of the SPAN. The comparison test was done on 1368 with a station (Taiwan) a bit below the nominal (see fig. 2) and also other tests showed that the accurancy of frequency measurements is about 2 Hz – generally about 2-4 Hz. Maybe later on we will have the span reduced to e.g. 200 or 500 Hz?

Selectivity is good and at least at the same level as that of the IQ/14 and a bit better than that of the ICOM R9000 or AOR (with SSB filters around 2 kHz). And you can adjust it how you want – also “asymmetric way”. You can also move the center frequency – about as PBT does. There are buttons also for the notch and PBT but they seems not to be active yet – this feature is coming later on, I suppose.

Recording – Span Capturing (“Drift Net-DX”) is straightforward, you have just to decide whether you want to capture a slice of 100, 200 or 400 kHz, push the button and use the recorder-buttons on a lower left corner of the window. Actually you can even record a bit more (almost 500 kHz with 500 kS/s sampling?), but there can be false signals on both sides?). As mentioned earlier the play-back feature differs from that of SpectraVue a bit: you can not jump just back and forth. Instead, you can assign a portion of the recording for looped play-back. And there seems still to be some problems with the operation on playing back – I could freeze the computer using that and had to switch the power off once. Note that you should have the unit on – so you can not listen the files with another computer and/or at another place without the hardware using the Perseus software, what is possible with the SpectaVue and SDR-14/IQ. However using the WinRad-softaware you can do playback also without the Perseus hardware, which is good although there are some limitations using that one as there are no timestamp at the timeline and not even the stop button on WinRad´s timeline. You get 10 minutes recordings with the software automatically (about 1,7 Gb each). You have also to give the name to the files all the time before starting to record and the software puts the sequence numbers after the name like 1,2… The timer is not included, but there is a possibility to do a timer with windows macros, but I have not yet tried that. The timer function like that of IQ – Spectravue could be greatly appreciated! After this report was written I have heard that the "official" release of the software (1.0) is due out in February - maybe something of the wish list are in that version.

I used mainly my desk-top (a bit old) model of a Pentium 1.8 GHz machine with 1 MB internal memory. The software took about 30-40 % easily at 125 kS/s and when switched to maximum sampling rate of 500 kS/s in order to capture 400 kHz to the hard disk, it took about 80-90% of the resources. So with my setup, I can not use both Perseus & IQ at the same machine. I also had some play-back problems with this set-up, and had to start the playback again, which actually worked to that problem. Using my laptop of Pentium (1.3 GHz only, IBM T40) was about the same, but it seems this machine works better showing the maximum usage of resources at about 60-70 %. I have heard these small IBMT40´s really performs like about 2 GHz machines. I did not tried to record to external HDs, but it should work ok and that has been done by other testers without problems. I think that with modern pc´s of about 3 - 4 GHz and 2-4 GB memory these problems are not present.

All-in-all I have to say this is a great piece of equipment – good looking software with great capabilities – and the software is still in Beta-state – so what are we getting when that is the final version. Well Done Nico Palermo & Microtelecom!

Last but not least, I would like to thank all the impressions of earlier testers of the rx like Bjarne Melde, Guy Atkins and Giampiero Bernardini at their blogs and emails as well as Mauno Ritola & Jussi Suokas (& all the “DXing Wolfs” in Eastern Finland) who were the first in Finland to test the machine. Now we have the DriftNetter of 400 kHz, next year at least up to 2 Mhz or ?


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