Bendix gear end clamp

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Not Jim but...

This web site is pretty good with supplying info:

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It is basically a software programmable radio. Can be easily customized to do all sorts of nifty stuff by programming. Like spectrum analyzer, FM narrow or wide-band radio...

=== What is RTL-SDR? RTL-SDR is a very cheap ~$25 USB dongle that can be used as a computer based radio scanner for receiving live radio signals in your area (no internet required). Depending on the particular model it could receive frequencies from 500 kHz up to 1.75 GHz. Most software for the RTL-SDR is also community developed, and provided free of charge.

The origins of RTL-SDR stem from mass produced DVB-T TV tuner dongles that were based on the RTL2832U chipset. With the combined efforts of Antti Palosaari, Eric Fry and Osmocom (in particular Steve Markgraf) it was found that the raw I/Q data on the RTL2832U chipset could be accessed directly, which allowed the DVB-T TV tuner to be converted into a wideband software defined radio via a custom software driver developed by Steve Markgraf. If you've ever enjoyed the RTL-SDR project please consider donating to Osmocom via Open Collective as they are the ones who developed the drivers and brought RTL-SDR to life.

Over the years since its discovery RTL-SDR has become extremely popular and has democratized access to the radio spectrum. Now anyone including hobbyists on a budget can access the radio spectrum. It's worth noting that this sort of SDR capability would have cost hundreds or even thousands of dollars just a few years ago. The RTL-SDR is also sometimes referred to as RTL2832U, DVB-T SDR, DVB-T dongle, RTL dongle, or the "cheap software defined radio".

There are now many other software defined radios better than the RTL-SDR, but they all come at a higher price. Currently we think that the Airspy ($169) and SDRPlay ($99) SDR's are the best low cost RX only SDR's. There is also the HackRF ($300USD) which can both transmit and receive... ===

Reply to
Leon Fisk
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Thanks Jim. I'll take a look. Regarding the first, do you know what a rtl-sdr is? Not a resistor transtor logic device?

Hul

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It's a low cost DVB-T digital TV tuner that also functions as a wideband

8-bit digital radio receiver. I bought this 14-bit receiver instead:
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-jsw

Reply to
Jim Wilkins

... It's worth noting that this sort of SDR capability would have cost hundreds or even thousands of dollars just a few years ago.

----------------------------- I built developmental prototypes of I+Q digital radios at Mitre in the early

1990's that cost the government tens of thousands. It's an old idea that became practical with the availability of the hybrid and then integrated high speed A/D converters that enabled digital storage oscilloscopes, and the complementary direct digital synthesizer (waveform generator) chips to modulate the transmitter. I happened to have considerable experience with A/D converters and computer circuits which the radio techs didn't so I got the job.

I should have paid more attention to the math of the square root of -1 in college but I was sure I'd never need it. When I began working with I and Q I had to take night school math classes to keep up, and an amateur radio license course to learn more about radio circuits.

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"It turns out that any form of modulation can be performed simply by varying the amplitude—only the amplitude—of I and Q signals, and then adding them together."

We used 8 phase modulation which packs 3 bits into each transmitted symbol. The CPU was usually a TMS320xx digital signal processor. That's why I don't have much experience with the ARM family.

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Reply to
Jim Wilkins

Originally had a FCC Class 1 license with Radar endorsement. FCC eliminated it along with the Class 2 soon after I got it. Replaced with the General Class...

Been out of it for ~20 years now. My last service monitor, that had a spectrum analyzer built in sold for ~$35,000 new. We picked it up as factory demo unit for less. It only covered ~100khz to 1ghz. Weighed maybe 30 lbs. Was certified though for accuracy...

I have one of the RTL-SDR.com USB dongles. It just blew me away with what could be done for ~$30 a few years ago. I'm looking at it hanging next to a waiting USB cable right now. If I plug it in my afternoon will become toast, fooling around with it. I purposely avoid it like it's crack coke...

Reply to
Leon Fisk

"Leon Fisk" wrote in message news:sc7dds$7au$ snipped-for-privacy@dont-email.me... ... I have one of the RTL-SDR.com USB dongles. It just blew me away with what could be done for ~$30 a few years ago. I'm looking at it hanging next to a waiting USB cable right now. If I plug it in my afternoon will become toast, fooling around with it. I purposely avoid it like it's crack coke...

Reply to
Jim Wilkins
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I have a version of GNU Radio loaded but scared of the time I'll burn through once I begin looking at it:

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This would have been so cool and useful to have back when I was still working in the trade...

Reply to
Leon Fisk
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I have a version of GNU Radio loaded but scared of the time I'll burn through once I begin looking at it:

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This would have been so cool and useful to have back when I was still working in the trade...

Reply to
Jim Wilkins

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