Ham radio documentary

[Strat]

I discovered this documentary recently. It shows some of the things you can do and what a fun hobby it can be. I thought 'moon bouncing' was really cool. It's a fun intro into ham radios and is entertaining.

(25:00)
wt5wZhC5crI

[Casey Claar]

Thank you for posting, Strat!.. queueing it up now.

[Szymon]

Looking forward to watching this. Thank you Strat.

[ExomatrixTV]

How to get yourself a cheap wide band receiver radio for less than $50 AUD, but there is a catch! (https://projectavalon.net/forum4/showthread.php?120942-How-to-get-yourself-a-cheap-wide-band-receiver-radio-for-less-than-50-AUD-but-there-is-a-catch-):dog: (https://projectavalon.net/forum4/showthread.php?120942-How-to-get-yourself-a-cheap-wide-band-receiver-radio-for-less-than-50-AUD-but-there-is-a-catch-) (https://projectavalon.net/forum4/showthread.php?120942-How-to-get-yourself-a-cheap-wide-band-receiver-radio-for-less-than-50-AUD-but-there-is-a-catch-)

[ExomatrixTV]

I Know There Are Software-defined Radio Receivers, But Are There SDR Transmitters Too?

Sure. When speaking of Software Defined Radio, the implication is that you’re making a whole radio via that technology, transmit and receive. And they’re all over the place.


The Military’s JTRS radios are full SDR. This allows various different waveforms to run, and new ones to be added.
Most LTE cell sites are full SDR. This allowed, for example, a changeover at Sprint from WiMax to LTE, and it’s allowing LTE Advanced to be rolled out without a huge new investment in hardware.
SDR transceivers are fairly popular in HAM radio these days. It’s not just for scanners.
SDR is moving rapidly into IoT, where the number of different radio protocols, the ability to update large control networks, cost, and the fairly low bandwidth needed for most IoT nodes is making SDR viable.
The increasing number of different radio types is quickly pushing SDR into moblile devices.

What most people want in an SDR is really the combination of a Software Defined Radio and a frequency agile RF front end. Once you’re dealing in even reasonably broadband signals or tuning ranges, you do need a real RF front end into the ADCs and out of the DACs that enable the “software” part of your SDR. It’s much easier to build an agile receiver than transmitter. And of course, some people just want SDR to enable a wide range of receiver frequencies. But someone has to do the transmitting!


Back When I Played This Game

At a company I left some years back, I worked on both agile tuning and software radio, though curiously, not in the same project.

https://qph.cf2.quoracdn.net/main-qimg-e4d7c19af2c4aa4f15dcf3f5a0f57efe-lq

Here’s the “Agile AWE”, an agile radio front-end and frequency transverter I designed in 2009–2010. This could tune between 50MHz and 2000MHz, and back then we were feeding the output at 2350MHz into a WiFi chipset, rather than a software radio back-end. So this was frequency agile without the SDR part.

SDR was possible in those days, but expensive. On another project, I wrote a software receiver for NTSC televsion, as part of a video server designed to aggregate conventional television signals (usually on weird frequencies) from drones or robots as well as M-JPEG streams from other robots and output a DVB-H multiplexed stream containing each source in MPEG-4. I built an 8-core server using two Core 2 quad systems in a 1U rack to manage it. The SDR was using two USRPs (Universal Software Radio Peripheral), but as mentioned, receiver-only in this case. The USRPs weren’t true agile radios, but they had modular RF front ends for different frequency ranges, some TX/RX, some RX-only. And that was a huge heap of computing power there to get around the need for a couple of $1.50 NTSC receiver chips.


Careful When You Say “Software”

When you first learn about SDR, or get a hobby-level SDR kit, it’s probably a pretty simple concept: you’re more or less connecting that antenna straight to your ADC, reading in that raw stream at some reasonable sample rate, and building software processing blocks to turn whatever you picked up into a useful thing. And I already mentioned that in practical systems, the antenna may have to run through a full RF front end and tuner before it’s handed off to the land of digital.

Beyond that, yeah, it could be your CPU getting everything. But that’s usually a waste of heat in the real world, simply because standard CPUs are good at general purpose computing, but not ideal for signal processing. So the software might be runinng on a Digital Signal Processor (DSP) instead. That’s another kind of CPU, but optimized in various ways for efficient signal processing. It might get processed by a Field Programmable Logic Array (FPGA), a “programmable chip”. Some types of FPGAs actually store their circuit layout in RAM, and can be reprogrammed on the fly for different activities. For the right application, an FPGA can process signals 1000’s of times faster than a vanilla CPU, using much less power.


Read More:

A rare look inside an LTE cell site, operated by Sprint in San Francisco - ExtremeTech (https://www.extremetech.com/extreme/158342-a-rare-look-inside-an-lte-cell-site-operated-by-sprint-in-san-francisco)
Ham SDR Resources (https://hamradioscience.com/resources/)
The leader in Software Defined Radio (SDR) (https://www.ettus.com/)
12 Popular Software Defined Radios (SDRs) (http://blog.bliley.com/12-popular-software-defined-radios-sdrs)
10 Popular Software Defined Radios (SDRs) of 2022 (https://blog.bliley.com/10-popular-software-defined-radios-sdr) :dog:

source (https://www.quora.com/I-know-there-are-software-defined-radio-receivers-but-are-there-SDR-transmitters-too)

[Szymon]

Thanks again Strat. I just finished watching it and yep I still love it.

Cheers,
Szymon