Thursday, March 22, 2007

SDR-IQ Suitable For MW DX?

Still "naked", i.e. without an enclosure, I tested the IQ last night as conditions towards North America were quite good. Also connected to my 175-meter beverage was an Icom IC-746Pro and an IC-7000. I started out late evening when European signal levels were rather high. Around 2230-2300 UTC one can hope for the first NA stations to fade in. For the first time I could actually see them before I heard them thanks to the waterfall display. First in with audio was WLQV Detroit MI 1500. At more or less threshold levels, there was no significant difference between the IQ and the 746Pro with regards to audio response. The 746Pro does have a warmer sound mainly because it has treble and bass controls but that was about it. The IQ's bandwidths provide excellent rejection of adjacent-channel interference.

A few hours later after some sleep I programmed Spectravue to record RF from 1325 to 1475 kHz, autosplit into 1 GB (26 minutes) timestamped files. I recorded around two hours. As I am writing this at home, I am tuning around and finding commonly heard NA stations as WLOL-MN 1330, KRNT-IA 1350, WTAQ-WI and KRKK-WY 1360, KDTH-IA, KSUM-MN and KXTL-MT 1370, KOTA-SD and KLIZ-MN 1380 etc. etc. And one much less common, KIGO-ID 1420. Audio quality is excellent, both on AM and on ECSS for those stations close to European stations.

In retrospect I see that a file size corresponding to 26 minutes is a bit too small. Maybe one hour is better - a bit over 2GB. Of course one could collect a full night's RF recording into one single file. There are pros and cons whatever you choose.

The somewhat limited sensitivity I reported a few days ago does make some difference compared to my other receivers, but only when the signal levels are low; around and after sunrise.

The IQ has not been calibrated since I got it. I will probably do so, but in my case there is very little to gain. It is very accurate. In fact, so many US and Canadian stations being slightly off their frequencies is a much bigger problem.

SDR-IQ Suitable For MW DX? SDR-IQ Suitable For MW DX!

1 comment:

Bjarne Mjelde said...

Mauno Ritola kindly reminded me that max. filesize is 2147 MB; this is clearly stated on the Output Setup dialog box. That should equal 56 minutes on a 150 kHz span. Spectravue 's timer should have had the option to enable a timer every 60 minutes. Start 4:30, end 0:30. Perfect for ID's following news, and ending with a TOH ID...