GPS Survey Antennas
I've recently become interested in dual frequency GPS receivers - the kind the are used for land surveying and geodetic research. More on that in another post. But along the way I've collected a whole bunch of antennas for these…
USR-IOT Serial-to-Ethernet Converters with Linux
I'm posting this mainly because Google didn't turn up any help when I queried about using the USR-IOT serial port to ethernet converters (also known as terminal servers) with Linux. They make several low-cost devices that are really handy if…
GPS Frequency Stability
I couldn't find a nice graph showing the timing performance of a single-frequency, sawtooth-corrected, pulse-per-second output from a GPS. So I measured a CNS-II GPS Clock and a surplus telecom HP Z3805A GPS Disciplined Oscillator (GPSDO) against a high-performance Cesium…
Mini-Circuits Power Amp
Each year at the Dayton Hamvention, the folks at Mini-Circuits have a bunch of odds and ends they sell very inexpensively. Over the years I've gotten tons of SMA attenuators and jumper cables, and a few amplifier blocks. I'd never…
Oscillator Aging Trends
It's well known that just about all oscillators drift, or "age", in frequency with time. In crystal oscillators, the most drift occurs when the oscillator is young, and over time the aging rate decreases. Power-cycling the oscillator results in a…
Peak vs. Average Power in Complex Waveforms (and Gnuradio)
One of my Gnuradio projects is a tool that records IQ data covering 375 kHz -- which is enough to capture an entire HF ham band (except for 80/75M). A neat trick is to retransmit such a recording to allow…
HP 5065A Status
My faithful HP 5065A Rubidium standard, which had been converted to a "Super" model, developed an intermittent sickness and back it went to Corby Dawson for him to perform his magic. After a realignment and fixing an intermittent connector ground,…
Anan7000/HPSDR and Icom IC-7300 S-Meter Calibration
I've noticed that my SDR setup, an Apache Labs Anan-7000DLE transceiver used with the PowerSDR software, seems to rest the S-Meter at a quite high level when there is no signal present. This is unnerving when I try to compare…
HP 5061B-004 Cesium Standard
I was lucky enough to find an HP 5061B cesium standard with what I think is a virtually new high performance (option 004) tube. These are rare because the high performance tubes burn up their cesium supply much more quickly…
HP 5065A Rb Standard
I set my HP 5065A Rubidium standard to the 5071A. Unlike a Cesium clock, the Rubidium system does have some drift so it needs to be tweaked occasionally. I plan to come back to this post every few months to…