The KONG HQ is Ready (Almost)

 I did some antenna work this and last weekend, along with SDR testing. Last weekend I rolled out the 50-degrees beverage antenna in sunshine and 20 Celsius. Not quite high today, but 15 Celsius is still warm for 1st September. Cloudy and a little breezy. Having spotted no reindeer, I elevated the 50-degrees beverage to an average of 130 cm. I also rolled out the 310 degrees beverage, which points roughly towards Chicago. It has an average height of around 200 cm.

"Far end" of the 50-degrees beverage

"Looking home" towards the feedline of the 310-degrees beverage

What remains to do is to deploy the staggered 340-degrees beverage, and to ground and elevate the 80-degrees beverage.

Perseus22 testing continues. Phasing the 50 and 80 beverage wasn't a good idea, they were too close in performance. I have now replaced the 80 with the newly erected 310 for a better difference in directivity. And finally, one for the food lovers:

Junipers! Not often ripe at this latitude. Great for flavouring reindeer and lamb meat

The RigExpert Fobos SDR

New SDRs do not come very often, so they are usually worthwhile to check out. The Fobos SDR from RigExpert in Ukraine looked like a novel design with promising features. I got it a little over two weeks ago, and my first impressions did leave some question marks. You can read the blogpost here.

Further testing unfortunately lead to a negative conclusion. This is not the SDR you should buy. At least in its current configuration.

And here is why.

Fobos SDR Is Here! But There Is a Catch...

 Arrived last Friday. The Sunday before I had brought the signal generator with me from the KONG HQ in anticipation of its arrival, since it was unlikely that I could go there this weekend for testing. A 10k run on Saturday got all the attention (and rightly so since I did a PB on the run).

Its blue box with yellow elements such as the five SMA connectors creates a nice tribute to its Ukrainian heritage.

Anyway: I have tested the device. Installation was almost as straight-forward as I expected. I have tested the Fobos SDR with HDSDR 2.80 and 2.81 beta 6, and SDR# (version 1716). It weighs in at 143 grams. Less than one-tenth of the 2-MHz Perseus22.

A few pictures follow. I wonder how they're going to open the box if they need to service it. There is nothing for a screwdriver or torxdriver to connect to. "No serviceable parts inside"?

I should have checked the block diagram more carefully before I bought it.  I was quite surprised that sensitivity on the HF1 and HF2 antenna inputs is pedestrian, to say the least. I measured around -85 dBm on 1000 kHz, actually up to 20 dB worse than other SDRs I have! Now, the block diagram indicates that the LNA only activates in "RF mode", i.e. from 25 MHz and up. So, there is no amplification in the <25 MHz (HF1/HF2) range except the LTC6401 chip.

So, that's where the LNA is hiding

What a strange omission. And why on earth didn't I notice.

It does sample 50 MHz. But the lowest sampling rate is 8 MSPS, not 4 as indicated on their web page. They need to offer lower bandwidths as well. 

It is very light on CPU. Sampling 50 MHz was handled with ease on my four years old HP AMD PC. Recording 50 MHz - well I'm not sure that it was stutter-free, but it didn't crash the application or the PC.

It is quite warm to touch when sampling 50 MHz. 8 MHz was a lot cooler.

Here at home I have no antennas, so it's really quite limited what I can do. And I really need to talk to the people at RigExpert about this. Hopefully, one of the coming weekends I will be able to test how it performs on FM at the KONG HQ, compared with the RSPdx.

More as it happens.

RigExpert FobosSDR

 After some delays over the summer, the FobosSDR from Ukranian company RigExpert is now available. I just ordered mine from wimo.de for EUR 415 (export). GigaParts in Tennessee wants USD 390, but is out of stock as I write this. With a 14-bit ADC resolution, up to 50 MHz sampling rate and two channel direct sampling on the frequency range below 25 MHz, this one may be a very interesting addition to the SDR world. Oh, and it tunes up to 6 GHz. Hardly of interest to the MW DX-er, but there you are.

We will see! When it arrives!

More on the Perseus22 (And a Foggy KONG HQ)

With version 1.2 of the Perseus software out I was hoping to see the implementation of some essential functions for the MW DX-er. However, it was mostly fixes and improvements. I did have a chance to test the WRTH database though. While connection and loading of the database was instant, the results were underwhelming. It seems to me that the WRTH database is far from accurate. One of several examples on the 19-metre band (the only band I checked) is shown below. No it's not Radio Habana Cuba, it's the Voice of America.

Also, MW stations are not listed at all.

There are many databases available. For MW DX-ers a regionally filtered version of MWList would be a lot better. For SW DX-ers I suppose anything but WRTH is better. Sorry to say.

Below is the business end of the Perseus22, namely the back panel. The SMA to BNC pigtails on HF1 and HF2 are tailor-made from Bonito in Germany.

The four channel windows are adjustable in height and width and can be moved around. Below are three of them, HF1, HF2 and VHF1 (the DAB+ band).

After a wet and rather chilly June, we've had dry and warm weather this summer. Coastal areas are exposed to fog though, and yesterday evening it was "thick as peasoup" as we say here. The KONG HQ seen from the beach, 60 metres away.

Perseus22: Increase your hard drive budget

The IQ files from the Perseus22 are proprietary, with the extension p22. So you can't read its properties like you can with a wav file. Since I thought the megabytes added up rather fast, I decided to find out exactly how much.

If you record one channel only, the IQ file will increase with roughly 15 MB per second.  If however  you record two channels (HF1 & 2, or VHF1 & 2), it will double. Which is quite natural. So, we're talking around 30 MB per second, or 108 GB per hour.

Compared to the original Perseus, which also records IQ files off a 2 MSPS range, it only uses around 7.5 MB per second. More exact: 61,000 bps. Now, Perseus recordings are 16-bit, so I'm quite confident that the Perseus22 is using 32-bit recordings.

Now, isn't a 32-bit recording better than a 16-bit? In theory, yes. In real life, no. Several years ago I spent quite a few hours comparing 32-bit recordings from the Winradio G33DDC with Perseus recordings. It was impossible to tell the difference.

It would be nice if Microtelecom/Elad made 16-bit recordings optional in a software update.

Perseus22 - Evaluation

So, after having tested the Perseus22 to the best of my abilities, I did a 10-page evaluation based on its current software version 1.1. Although it must be regarded as a rather unfinished product, at least with regards to parts of the software, it shines in other areas, like nulling and enhancing signals, not only in live mode but from IQ recordings as well. I spent a few hours testing it out, and it didn't disappoint! Report is here.

Enjoy!

Perseus22 - Skins

Which program was the first to use "skins"? Winamp? People have different preferences with regards to how they want their software to display on the monitor. Perseus22 offers three variations; User, Army and Hewlett. In addition, the "User" skin is configurable beyond belief - so instead of "skins" maybe Perseus22 should have offered a suite of "Styles". The current default skin looks good, but suffers from small fonts and unsatisfactory contrast. Especially as age has taken its toll on vision. And admit it: Which 20-year old will buy a Perseus22?

Anyway, below are the three skins currently (July 2024) available in Perseus22:

Default "User"

"Army"

"Hewlett"

If of interest, the three images were made when I had two antennas connected to the HF ports, one (left) sampling the 19-metre band and the other sampling the 31-metre band.

 

Perseus22 - DAB

 Back at the KONG HQ after a couple of weekends spent running! First, Midnight Sun Marathon in Tromsø on June 22 doing a half-marathon that exceeded my expectations. A week later I attempted a Backyard Ultra in Kirkenes, near the Russian border, where I bailed out after six rounds and 40 km. Thighs still aching.

 Now: Vacation! So, I thought I'd connect my FM antenna, pointing perpendicular to the DAB transmitter in Kongsfjord, to the Perseus22. No problem. The DAB transmitter is only 4 km away and 100 watts.The only available MUX here is the NRK MUX, comprising 18 channels including my favourite NRK P13. The screen dump below shows how DAB+ is received. Indeed, I have my doubts if legacy DAB is decodeable, as the manual specifically mentions DAB+ and not DAB. As far as I know, legacy DAB is only available in the United Kingdom now. Maybe someone in the UK could confirm.

With the "Snap DAB Freq" option selected, one can move from MUX to MUX by scrolling the mouse up or down. No keyboard up/down entries available in version 1.1.

No program info (show, artist, title, image/logo) is available in this version, unless I have overlooked something. Channel selection is excellent, instant decode.

Perseus22 - Some Observations

 It's far too early to pass any judgement on the Perseus22 on my side. For instance I have had no opportunity to evaluate one of its core features: Correlation/decorrelation. Still, here's what I've learned from a few hours of use.

The SDR itself is stunning. And heavy! 1723 grams on my digital kitchen weight!! The manual says 1680 g. Whose weight is wrong? Almost as heavy as the Elad FDM-S3. But then, who would have considered a 2 kg communications receiver heavy 20 years ago.

A few observations:

Sensitivity is slightly better than the original Perseus, 2-3 dB better on MW, equalling -106 to -107 dBm (AM, 6 kHz bw, 30 % modulation of a 400 Hz signal for 10 dB S+N/N).

Four DDC sampling rates: 0.25, 0.5, 1, 2 MHz. Alias-free bandwidth appears to be 0.2, 0.4, 0.8 and 1.6 MHz as with the original Perseus. The 2 MHz bandwidth also applies for FM. The bandwidth should allow reception of one DAB MUX (1536 kHz).

The hardware has an on-off button. Why on earth etc. A PC restart did not require a physical "on", but moving the hardware from one PC to another did. And alas... so does a real power outage. This might seriously limit remote control - on the other hand I had the same problem initially with the FDM-S3 so maybe it resolves.

Direct frequency entry is a lot easier than with the original Perseus. Just tap the numbers in the active window and press Enter.

You can have several "radio windows" open, probably one for every antenna. A clever twist is that only the window in focus submits audio - the others are automatically muted. No need to turn off and on audio.

HF2 (9525 kHz) is muted, while HF1 (1557 kHz) submits audio

IQ recording: The resulting IQ file is proprietary with the extension "p22". I tried to change the extension to "wav" and open the file in HDSDR and SDR Console, but no cigar. So, what you record with the Perseus22, you need to play back with the Perseus22. You're not required to have the receiver physically connected to the PC though. It loops playback automatically - which is good because at this stage there are no other commands available to the playback mode except "Open File".

When running in 2 MHz mode, my power supply says current is around 1A. A 9VDC power supply is required. Unfortunately the submitted Mean Well switching PSU is not quiet, at least not on the MF and LF range. And why 9 VDC? The FDM-S3 can take anything from 8 to 15 VDC. The manual warns strongly against using anything else than the power supply provided with the receiver (section 4), and doing so actually voids the warranty (section 1.1). There is no indication in the manual that the SDR is protected from higher voltage input. An omission that fried many legacy Perseus SDRs.

Correlation/decorrelation: I haven't tested properly yet, I need to put up a couple of decent antennas. And currently the MW band is dead as a dodo here. Other users report good results nulling local noise and groundwave stations. To do this, you obviously need two antennas, where one should serve as a "noise" antenna. It would be wonderful to have decorrelation of skywave signals, but I don't expect to see that.

So far, tuning is available only with mouse control - apart from the excellent direct frequency option. Up/down/left/right arrow keys do not work..

Tuning options (frequency step, snapping) brings you all over the place. It snaps ok, but not at the assigned frequencies. 

I understand there is no API or SDK available. Will there be?

It's pricey.

I am sure (or at least I hope) that the software will improve over time. However, there are some GUI design and cost issues that do not quite appeal to my usage. Thank dog for the legacy Perseus.