SDR-14

[Mike/W8BAC]

Has anybody tried this receiver? Frank?

http://www.rfspace.com/sdr14.html

Mike

[kf6pqt]

Neato, how much$?

[KA8WTK]

U.S. price $1099, according to their order page.

[W3LSN]

Has anybody tried this receiver? Frank?

http://www.rfspace.com/sdr14.html

Mike

I've owned an SDR-14 for a while and love it. I was really looking for a software defined radio that was more analyzer than radio, and with the SpectraVue software that comes bundled with it I get the best of both worlds.

73, Jim
WA2AJM/3

[Mike/W8BAC]

The spectrum analyzer is very nice. One thing that I like is the TIVO like recording ability of a section of the spectrum for later playback. I know that is software and not the black box. Man, 12 hours or more of recording and than play it back, tune up and down the bands, change modes and so on. Really cool.

I'm wondering how this box stacks up to high end "all in one" receivers.

[KF1Z]

Ok, I admit it..... maybe not thinking straight....

What am I missing?

What is the major difference between the SDR-14, and the SDR-IQ   ?

Other than the way obvious $1100 for one, and $500 for the other?

I couldn't find a list of specs for the SDR-14.... to compare with the specs for the "IQ".

Must be there somewhere................

[W3LSN]

The spectrum analyzer is very nice. One thing that I like is the TIVO like recording ability of a section of the spectrum for later playback. I know that is software and not the black box. Man, 12 hours or more of recording and than play it back, tune up and down the bands, change modes and so on. Really cool.

I'm wondering how this box stacks up to high end "all in one" receivers.

Mike,
I've never used the recording feature on mine so I can't offer much insight there except to say that you can record an ENTIRE 30 MHz chunk of spectrum which can be played back anytime using SpectraVue to tune in any signals it captured. You are not recording audio, you are recording a chunk of spectrum. Recording time is limited only by the capacity of your hard drive.

Having the spectrum display is quite nice because it tells me so much more about the signals I'm receiving. I never realized, for instance, that CHU on 7335 is running only one sideband plus carrier. I particularly enjoy watching various stations on 75 meter AM while checking their occupied bandwidth and density of modulation. I also like the tunable demod that lets me keep the spectrum in view while I tune up and down a slice of spectrum. I can vary the filtering on AM signals from a few hertz up to many, many kilohertz. I typically monitor BC AM stations at 10 khz bandwidth, and amateur AM stations from 3 khz up to 15 khz. I’m able to identify several digital modes on sight, and the display allows you to see stations that may be too weak to copy aurally. This is how I can usually tell when Henk, PE1MPH and his friends are active across the water.

As far as how the SDR stacks up against a top of the line all-band receiver, I think the traditional receiver might win out in terms of ease of use. The package is really a spectrum analyzer first, and a radio second.  The SDR-14 is not the equal of a lab grade analyzer by any means, but I’ve rarely heard anybody complain about its quality. Someone recently took the SDR-14 on an expedition to the radio observatory at Arecibo, PR to record pulsars on the big antenna.

There is now a cheaper version called the SDR-IQ which doesn’t have a chassis and some of the super-wide bandwidth functions. The IQ tunes all the way down to 500hz which is useful for people into VLF and “natural” radio sounds whereas the SDR-14 is only good down to about 30 khz. The SDR-IQ is only $400-$500.

So far the only software written for the box is SpectraVue, but the USB port is fully open and there is a developers kit if you feel so inclined. There is also a SDR-14 support group on Yahoo which you should join if you are considering taking the plunge. Moe regularly checks in there and will happily answer questions about his latest developments.

Bottom line is, if you buy either unit you won’t be disappointed. Two thumbs up on this product from ‘AJM.

73, Jim
WA2AJM/3

[W3LSN]

While surfing just now I read that Winrad now supports the SDR-14 and SDR-IQ. This would give a much more user friendly interface for the casual radio user who isn't interested in the analyzer functions, but I see it doesn't support AM, only SSB and CW!

73, Jim
WA2AJM/3

[Bacon, WA3WDR]

We are starting to play with the 'IQ' at work.

So far we have only set the unit up with a 50 KHz bandwidth, looking at a 30 KHz wide receiver IF centered on 57 KHz, listening to 15 KHz bandwidth FM signals.  The software records a .wav file that appears to be based on the center frequency you tell it, and I and Q demodulation goes onto the audio channels of the .wav file.

I just started looking at the .wav files tonight, and I am starting to think that they may not be standard .wav files.  Mostly the boss has been using the 'IQ', and neither of us quite knows how to use it.  I just tried playing the .wav files on a conventional .wav player (WavePad), and the recordings seem to be super low in level, like .006 on a scale of 0 to 1.  Yet when using 'WaveVue' that comes with the 'IQ', level is not an issue.  There seems to be AGC from somewhere that prevents the recordings from being much higher in level.

All in all, it's cool.  I need to spend more time with this thing.  The boss sent it to somebody, so I can't play with it this weekend.

[Mike/W8BAC]

One interesting aspect is you don't need a dedicated sound card and a jungle of interface cables. A usb 2.0 connection is the only interface and provides power for the receiver as well. That makes it a very clean rig for travel. Now I need an SDA-14. A software defined antenna.

I am wondering about the recordings. Say you make a 12 hour recording of 30MHz spectrum. Do you have control over time during playback? If you miss something can you pause and rewind? I would want to grab sections of that recording and save to another file. Say your listening to a 30MHz wide swath. You find something on 7.290 AM with an 8KHz filter you want to save. Can that be done?

None of this matters if the receiver is noisy or numb. I own an HP 8558-B spectrum analyzer in an 853A digital display. It is an awesome analyzer but not a particularly sensitive receiver. I don't need another analyzer but a Super Receiver can always find a home here.

Thanks Jim and Bacon for the comments.

Mike

[W3LSN]

Mike,

I'm not sure about random access to parts of the file. I have never played with the .wav recording function so I'll need to try it myself sometime.  I know that the recording will reflect the current settings of the SpectraVue software, so if you have the span set to 30 MHz it will record 30. If you have the span set to 10 khz it will record that. You'll fill up the drive in a hurry recording the full bandwidth though so unless you have some significant online storage I don't think you'll be doing that too often.

BTW you can download a fully working copy of the SpectraVue software from the website and play with it yourself. You can do the same thing with Winrad or Linrad too. You just won't be able to test most of the features without the SDR.

I'd suggest that you join the SDR-14 and SDR-IQ Yahoo discussion groups which can answer all of your remaining questions. It's a good place to get information from other users worldwide and to talk to the developers. Moe Wheatley AE4JY who developed SpectraVue visits there regularly. Pieter Ibelings N4IP who runs RFSpace is there too.

73, Jim
WA2AJM/3

[Mike/W8BAC]

Jim,

Yes, 12 hours of recording at 30MHz of bandwidth would be a HUGE file and require a few terabytes of storage if not more. Who needs that anyway. They do say you can record 190KHz for a day (24 hours?) on 67.8 gigabytes. That's doable. I'll have to talk to some of the experts to see if the sub files can be made.

Thanks Jim

Mike

[WA1GFZ]

I think the SDR14 has a DDS source so as long as you don't mind spurs it is ok.
No real high performance receiver uses a DDS source. synthesizer crud or phase noise must exceed the dynamic range. The DDS usually has better close in phase noise than a synthesizer but at the expense of spurs all over the spectrum.
Most high end receivers have close in phase noise exceed the dynamic range a couple khz from center frequency and work their way down to -140 dBc around 100 khz off center frequency. I have measured this in Racals, Cubics, WJs. TCI/BRs.  The best DDS A.D. makes with a 1 gHz clock still has spurs at -70 dBC.
The DDS can be used as part of a PLL with great performance but not stand alone.
No amount of software can eliminate all the DDS spurs only limit them. They are caused when the DDS D/A jumps from 1 value to the next. When you have a 1 ghz clock and need to make 50 MHz output the D/A makes 20 different output samples per cycle. Timing and value of the D/A create the spurs. I bet the mil guys have a lot faster clocks in their DDS chips to make cleaner outputs. There are integrating tricks to reduce the spurs but I have not seen a DDS that outperforms a good pll yet. I'm sure they are out there but we can't afford them of buy them. Take a soft rock 6 and a HP8640B and you can make one heck of a rX with a computer doing demodulation. A Soft rock 6 off a 455 kHz IF is a good place to start. The R390A still has one of the cleanest LOs on the planet. It also provides a way to compare stock demodulation with SDR. You get used to the processing delay after a while listening to both. I do that a lot these days.
Start with a cheap interface and save your cash for something good.
The next generation of receivers will do A/D right off the antenna preselector.
The next hpsdr board will do this and there are some Itialians who just put a RX on the market a couple weeks ago with that configuration. Similar price to the sdr14.  fc

[W3LSN]

Mike,

I was away on vacation for the past week down in Nags Head so I'm just catching up. Here are two URL's on the SDR-14 that I think you might find of interest;

1. This links to a report on Dynamic Range Observations of the SDR-14 with the test data compiled by SM5BSZ. In it he basically concludes that while there is noise introduced into the A/D converter from the data bus, it can be mitigated by the use of a 25 dB preamplifier which will raise the noise floor above the undesired signals if so desired. This has the effect of reducing the SDR-14 dynamic range to -127 dBsat/Hz, but he goes on to conclude that it's still quite respectable, and not very different as compared to conventional amateur transceivers.


http://www.nitehawk.com/sm5bsz/digdynam/practical.htm

2. This link is to a three-way comparison and review between the SDR-14, the FlexRadio SDR-1000, and the Icom PCR1000

http://www.monitoringtimes.com/html/mtflexradio3.pdf

Happy reading.

73, Jim
WA2AJM/3

[WA1GFZ]

Thanks Jim,
I was wrong the SDR 14 is an A/D so need to study it. The HPSDR guys are looking at a 130 msample a/d with an optional 170 msample.
The A/D method eliminates the need for an LO so no stinkin DDS crud.
The HPSDR will be much higher dynamic range when the preselector is added.  Also just returned from a week at the beach and away from computer and radio.
gfz

[W3LSN]

Below are the links to the SDR-14 and SDR-IQ user groups on Yahoo. Much useful information about both receivers and the SpectraVue software is discussed there. These are very friendly groups for the tire kicker and SDR owner alike.

http://groups.yahoo.com/group/SDR14/

http://groups.yahoo.com/group/SDR-IQ/

73, Jim
WA2AJM/3

[Mike/W8BAC]

Thanks Jim,

I'll check them both out.

Mike

[KF1Z]

Have an SDR-IQ on the way.......

Should be a load of fun to play with.....

Will need to get a big harddrive.... but they are dirt cheap now.

Being able to record 190khz of band at a time should be fun.....

Listen to one qso, then go back, listen to another, in a different mode , etc.....

we'll see!!