About it's quality compared to WWVB, see the next section.
Wwvb radio full#
That means that if you don't need the speed at regulation and the full accuracy that a proper GPSDO can give you, a simple GPS receiver that gives you only a PPS can also be used as a frequency standard. Of course, the better your VCO gets, and the better you filter that control voltage, and the smartser you get at calculating the adjustment, the less overshoot and beat frequency you'll have. If it's higher than it should be, lower the control voltage to the VCO, and vice versa.
counters) and VCOs to generate reference clocks from the PPS signal – it's easy: I count the oscillations between two rising PPS edges (there's a lot of microcontrollers that can do that in hardware for you, without any need for running a counter in software). I know that people also simply use digital PLLs (i.e. Note that the LEA-M8F is much more expensive than your average GPS module, just because it's also supplying a reference frequency, not only location and PPS. Why are those more expensive than the typical GPS module?
Wwvb radio serial#
Then, one buffer for 30.72 MHz (or configurable frequency, IIRC) and PPS each.ĭon't know if it'll need special communication via the serial port headers soldered on below to start (don't actually think so!), but these could be trivially supplied using just any $5 USB-to-TTL adapter out there.
Wwvb radio generator#
The Opendigitalradio project (a project to establish broadcasting systems for digital audio broadcasting), or rather Matthias HB9EGM himself, has built a GPSDO:Īside from the uBlox LEA-M8F GPS receiver, reference clock + PPS generator module, there's barely anything on that board – a chip to regulate the supply voltage, and one to protect against ESD if one decides to solder on the USB debugging plug. You can find a lot of these modules on the surplus/used market – Trimble GPS comes to mind, for example – but you can also build such things yourself: Thus, in the professional world, WWVB and similar things are pretty much forgotten, since the signal simply is too narrowband to give you a good frequency and timing estimate within short time. GPS-discplined oscillators (GPSDOs) are really common in cellular base station technology, where you must very accurately coordinate frequency (and time), to be able to use the (billions of euros) licenses for the limited spectrum you've got most efficiently – avoid the guard band between you cell's "own" band and the neighboring cell, as well as minimize frequency-error induced losses in transmission. Frequency standards in cellular infrastructure You'll find a lot of modules on the market that will not only give you a Pulse Per Second (PPS), but also a frequency standard signal, most commonly 10 MHz, but there's other frequencies, too. GPS-based frequency answer rightly pointed at devices that use GPS to generate the 1-second pulsing.Ĭuriously, these modules only address the once-per-second accuracy issue, not the frequency standard issue, which GPS is indeed commonly used to solve:
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