Sunday, June 16, 2024

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.

Saturday, June 15, 2024

Perseus 22 !! First Looks

 So! It's here! Not mine though, OJ Sagdahl ordered it and handed it over to me while we were at Smøla HQ last weekend. Now it's at the KONG HQ, ready to be tested. 

(Edit:) Apparently drawing around 1000 mA at 2 MHz sampling, the DC in is 9 V.

The station is TWR Eswatini, closing down at 16:20Z. Captured on the 250-metre coax feedline from the 80-degrees beverage antenna (disconnected).

Next on the list: Sensitivity! More as it happens.