Thursday, December 13, 2007

Some More Perseus Impressions

Since I didn't succeed in making sensitivity measurements, I thought I'd compare the Perseus and the SDR-IQ in an A-B test today. I connected my signal generator to a splitter, connected the two SDRs to the splitter's outputs, and set up a 1000 Hz tone with 30% modulation. Both SDRs were put in AM mode and 6 kHz bandwidth. I then gradually recuced the signal level until the tone was lost in the noise. The one that lost the tone last would be the most sensitive. The SDR-IQ won by a couple of dB.

RF recording should be easier with the Perseus than with the SDR-IQ but isn't. The problem is that you have to name a file before it starts recording, so there is a dialogue box to pass just like with the SDR-IQ. Playback is also more cumbersome than with the IQ since you can't start playback in a specific point in the file. You don't know where you are until you've selected the point. And you can't jump back and forth in the file; you need to highlight a period of your own choice (except you don't know how long it is and when it starts) and play that period. It automatically loops though and that's a good thing. When playing though, the program keeps track of the time.

Also I miss the option to tune via the up/down keys and left/right keys. And when you use the mouse, scrolling forward in Perseus means decreasing frequency while in the IQ it means increasing frequency. So operating the IQ and the Perseus at the same time can be a bit confusing.

I also experienced a couple of crashes; one resulted in the need of a reboot before I could start the software again. Maybe it's a Vista issue. I also hoped that the AVG settings chosen at one session were saved and used again in the new session; apparently they are not.

The AGC settings (there are four; Fast, Med, Slow and Off) seem well chosen, but I would have preferred to have the option of determining the values of each setting.

And horisontal lines on the display with dBm values would have been great.

The above might indicate that I'm not satisfied with the Perseus. That is not the case. As stated earlier, the audio quality excels, and the bandwidth option is exceptional. And some of my issues could be because I haven't explored all possibilities yet.

Oh, and one last thing, and an important one: The switching PSU. It is not as quiet as I thought. It actually produced tones every 8 kHz, not in the Perseus, but in the IQ! I had it placed in a 4-way mains socket which also sent current to the splitter they were connected to. When I placed the PSU in a different socket the noise seemed to go away, or at least be greatly reduced. But I really want a stabilised PSU for my Perseus.


Unknown said...

Intresting. I look forward for more comparisions. I have an IQ now, and when the Perseus was released, I thought should I have waited? I´m very satisfied with the IQ , comparing it to nothing, because it´s my first "real" radio.

Anonymous said...

... but,i dind't get it.These are the first measured of sensitivity or comparasions with other SDR RX with AM signal in the world on Perseus? And in CW who wins?