HFU HF Underground
Technical Topics => SDR - Software Defined Radio => Topic started by: ChrisSmolinski on November 27, 2017, 2353 UTC
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Look what finally arrived in the mail today. Photographed next to the SDR-14, for size comparison.
From the first few minutes of use, seems pretty good. I will write up a full review and some side by side comparisons against my other SDRs. And then I will write some software for it :)
(https://i.imgur.com/hBNnvVA.jpg)
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An early review of the Airspy HF+ is available in the December issue of "Radio User" (UK).
Mike Richards got a preproduction unit and goes through the new design:
-coverage: LF to VHF (up to 260 MHz)
-using a new type of mixer (frequency changer) ahead of the ADC: 16 phase mixer, giving adequate rejection of harmonics up to the 21th harmonic, so there's no need to use a bank of many RF filters ahead of the mixer, also no need of high gain preamplifier
-using a low phase-noise oscillator
-using a Sigma-Delta 16 bit ADC, followed by a digital filter (design said to produce less quantization noise)
- from there, a decimation stage (as usual), then the output
From only a few days of use, Mike Richards noticed a "pretty amazing" strong signal performance on VHF (around 138 Mhz) and on HF (around 7 MHz).
The key components makers were not named. Maybe we are at the beginning of a new generation of (almost) low cost and high performance SDRs ?
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Here's a free download link for the entire issue for those interested:
https://vk.com/doc448173336_454112114?hash=909522e91419174a37&dl=GQ4TONRUGAZTG:1511623889:839c02fd4badd7debe&api=1&no_preview=1 (https://vk.com/doc448173336_454112114?hash=909522e91419174a37&dl=GQ4TONRUGAZTG:1511623889:839c02fd4badd7debe&api=1&no_preview=1)
Download link was found here, in case it no longer works:
https://emagazinepdf.com/2017/11/radio-user-december-2017/ (https://emagazinepdf.com/2017/11/radio-user-december-2017/)
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I've been generally impressed so far. I have run into some images down on the LW band from SWBC stations, Youssef said they are still tweaking things (this can be done in software, via new DLLs). I have not run across any images on MW or HF.
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Here a nice comparison by Nils Schiffhauer (DK8OK), between the Elad FDM-S2 & the new AirSpyHF+ with 12 audio samples.
All recording have been made on a 20 meter quadloop antenna.
https://dk8ok.org/2017/12/06/airspy-hf-what-you-hear-is-what-you-get/
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My comparison of the AirSpyHF+ vs the netSDR, with several audio recordings: http://www.radiohobbyist.org/blog/?p=2361
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I am wondering if anyone has used the HF+ for QRSS or WSPR receive? I use a cheap $22 RTL-SDR and it is very stable. I am sorry to say that I also have an Airspy Mini with a Spyverter and the Mini is not frequency stable enough, after a warmup, to use with these two modes. That to me is very discouraging. I am considering the HF+ but am somewhat concerned by what I found with the Mini which costs 4 times the price of the RTL-SDR. Any comments or experiences would be helpful.
Thanks,
Larry
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I've found the AirSpyHF+ to be extremely stable, frequency wise. I use it for SSTV decoding, as well as on the NDB band, and have not noticed any drift issues.
As a test I just ran WSJT-X for a while on 40m and got lots of WSPR decodes, including many from Europe even though it won't be dark here in the Eastern USA for a few hours.
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Thank you Chris. May I ask what did you see on the drift column? That is where my Airspy Mini fails. Even after several hours I see drifts of up to +/- 4 but not consistently. I'll see a group of Zero decodes and the next decode I will see numerous stations with -4 drift. I check the stats page and no one else sees the driftdrift. On the other hand I can fire up my trusty SDR-RTL and rarely see any drifting of other station and when I do others verify it.
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Hey Chris, took the plunge today. Read your reviews that you have done throughout, and decided to order the Airspy HF+. I did like the frequency coverage of the SDRPlay a lot but for my use, I think this will be okay. I love HF no doubt, but the amateur radio side of me wants to start dabbling in the 2m range. I have a Kenwood TH- K2AT handheld and really haven't used it. I don't have anywhere near the setup you do as far as antennas, but I still think I will enjoy this a lot. I've been messing with computers since 1984 with my first Commodore 64 and 1541 floppy drive inputting homemade programs. Now I can integrate. Utilities I love also. Where is Airspy located in the U.S.? Do you know? I also bought my adapters from Amazon since they were cheaper. I'm kinda' psyched!! :)