HFU HF Underground
Technical Topics => Equipment => Topic started by: DimBulb on January 25, 2013, 1802 UTC
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A new stand-alone SDR has (or is about to) hit the market:
http://www.commradio.com/
Yes Al, this one has some knobs and buttons...
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Hey, an SDR in drag :)
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That looks more like a traditional superhet with DSP. The only place I see SDR is in the marketing info :-)
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Receiver Architecture -Dual conversion super-heterodyne with low-IF , I-Q digital sampling, 16 bit DSP with digital audio CODEC
DSP algorithms for all demodulation: DSB-AM, SSB, CW, WBFM, NBFM and channel filtering.
One important feature for me is the lack of reception below 500/KHz
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Appears straightforward, and does not seem to require a working knowledge of Bonitistic Geometry.
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Local BADXer [Boston Area DXer].... Eric Cottrell has one of these. Hopefully he'll bring it to our meeting on Friday so I can try it out.
Yup, I got to play around with it a bit tonite, very small and compact. The speaker is mylar [almost waterproof] and mounted on the underside.
The four feet are big, maybe to lift it up so the speaker can do it's thing? No push button frequency entry, so tuning has to be "spun", but the rate is adjustable.
Has several filter options. Well lit panel. Has a rechargeable lithium battery that can be charged via a mini USB port. Battery is good for 12 hours. Also takes 6-18 V DC in.
I tuned around the bands a bit and it seems sensitive enough but even with the local noise, the background seemed quieter than than most receivers. Certainly NOT SDR in the Persius Respect! I'd like to mount one under the dash in my truck.
Eric said the one thing he didn't like is that the receiver powers on and off by pressing in the left [volume control] knob and during transport it is very easy to have it turn on and drain the battery. There is not lock out option to disable it.
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Here is Eric's own review of the radio ....
I have an interest in Software-Defined Radio (SDR), so I was interested when I heard about a new SDR receiver, the CommRadio CR-1. There was not much information, but I liked the potential of an upgradeable receiver. I bought one and have been using it for about three weeks.
The receiver is CommRadio's initial entry into the radio hobbyist market and there are some minor ramp up problems. My receiver had a minor assembly problem. CommRadio did a very good job resolving the problem.
The receiver has a solid feel. It is a miniature communications receiver. About half the height is due to big rubber feet. This allows sound to escape from the speaker on the bottom of the case. The speaker has a mylar cone, which should improve survivability in moist conditions.
The front panel has a big tuning knob with a depression for spinning, a smaller volume knob, and a few buttons. Tuning Step Size, Band, Mode, Scan, and Memory operations can be done via the front panel buttons. Tuning Step Size can also be changed using the tuning knob. Other functions, like filter bandwidth, and tuning range are changed through the menu system.
There is no Pass Band Tuning or Notch Filter. There is no RTTY mode that uses a shifted 500 Hz filter. The available selection of filter bandwidths depends on the mode (see the specifications as updates have changed the filter bandwidths). Some of these features could be added via updates in the future.
Depressing and holding the volume knob toggles receiver power. I have problems with accidental power up while transporting. A piece of wire wrapped around the volume shaft was used to prevent power up during shipping. The volume knob is almost as deep as the Tuning knob so it is easy for things to press against it while transporting.
The receiver uses an Organic LED (OLED) graphical display, which is low power and bright. The brightness is manually controlled.
The power options are very flexible. The USB port or 6 to 18 VDC through the rear panel coaxial connector can be used. I got the optional internal battery that can power the radio for about 12 hours with normal volume.
The radio uses around 1 watt of power so it is possible to operate it from a small solar panel. The internal battery requires more power for charging. A 9 volt 1.5 watt panel worked in full sun when the battery was already fully charged. I need to do some more experiments and measurements with a 12 volt 1.5 watt panel.
There is a high impedance HF antenna connection in addition to the 50 ohm antenna connections for HF and VHF/UHF. This is my favorite feature. I plugged in an AN200 loop and tuned around the AM band. I had good results using a 6 foot telescoping whip with a 6 foot counterpoise.
The internal battery option, telescoping whip, and counterpoise makes for a very small portable setup. I was able to setup on the roof of my car and pull in Voice of Turkey with very good signals. This is a small low power receiver, so do not expect room filling sound. Updates have addressed some of the low volume problems. Earbuds work well and others have used amplified speakers.
The VHF range covers a good amount of VHF spectrum. The UHF range is more limited for me as most local public safety use UHF-T band (470 - 512 MHz). It is handy to listen to the local ham repeater or get NOAA weather.
When the squelch level is changed, the setting has to be set by pressing the volume button before the setting becomes active. This is different from how similar squelch settings work on my Uniden scanners. Squelch only works on VHF/UHF FM mode so it is noisy between transmissions on the VHF aircraft band.
A great feature about the radio is upgradability. The company is listening to user feedback and actively fixing problems and adding features. I have applied two updates so far, which significantly improved the receiver.
The upgradability has the similar downside as with PC software. It can be shipped when it is functional, but does not have all the planned features. This causes a problem with doing a review because the radio will be different weeks after I write this. For example, the receiver does not have Wide FM to receive FM broadcast stations currently, but the capability will be added within a few weeks via an update. So I recommend a PC with an Internet connection to receive and apply updates.
I like the receiver because it is a decent receiver in a small low-power package.