Hi Cash. Here is a bit of a narrative and some comments from an amateur radio perspective.
I got into the time nuts hobby as off shoot from amateur radio. I was using a pc sound card to evaluate the frequency stability of some of my ham radios by looking at the change in "beat note" when receiving wwv in SSB mode. I realized that I couldn't use wwv as a frequency standard due to Doppler shift and in practice my radios with tcxo's were stable enough that it wasn't clear if I was seeing Doppler shift from wwv or the radios drifting. After some research I purchased a gpsdo from James Miller G3RUH which provided a suitable frequency source to replace wwv for my purposes. Later I wanted to see accurate that GPSDO was. To make a long story short.... Ended up buying half a dozen HP5370 and HP5335 time interval counters a Jackson labs fury GPSDO, two Z3805 GPSDO's, a thunderbolt, a BVA, a FTS1050, an HP105, two time source 2700's (with prs 10 rb's) various stand alone rb's, ocxo's, various HP5328 counters with 10811 ocxo's, an NTP server etc. Wrote some scripts using Ulrich's plotter software to log the data to text files and processed the data using John's time lab software (thanks !). Couldn't quite convince my self to buy a cesium standard and a time pod (figured I would end up wanting to get two or three of each once I started down that road.) I was (and am) more than satisfied with the performance of the G3RUH GPSDO for my amateur radio activities. At the time work involved long periods of travel so collecting data for a few weeks at a time then looking at it later worked out ok. Later I also had little time or interest for Amateur radio due to travel. After a few years I decided to get back into amateur radio. I still use the G3RUH gpsdo to check the frequency of my VHF and up gear. It works well for this as it produces useable harmonics to over 1.3 GHz and it runs from a 13.8 volt power source. From time to time I still compare the G3RUH GPSDO to my other references. I have found for VHF and up weak signal work it is very helpful to have a suitable frequency standard. Regarding frequency calibration of my radios. In practice listening to harmonics from the G3RUH GPSDO with the radio set to SSB mode and looking at the resulting audio frequency works well for me. So far I've resisted the temptation to modify my radios to accept an external frequency reference, but checking their accuracy prior to use is part of my setup routine. I suspect at some point I'll acquire radios that need an external reference source. I've ear marked a few ocxo's for this purpose. Time synchronization is also important for some of the weak signal modes and having my own NTP server is helpful. For amateur radio use (with some time nuts interest) two GPSDO's, a decent time interval counter and a frequency counter capable of measuring frequencies of interest (and able to accept an external frequency reference) along with a PC with a sound card is probably a good starting point IMHO. A solution for time synchronization is also worth having especially for operations in locations without Internet connectivity. A GPSDO with a one pps output can help facilitate this. In terms of hints. Quality double shielded cables are useful. Conversely cheap cables caused me various problems. Terminating un used connections is also helpful. A decent oscilloscope is useful for viewing wave forms and looking at signal levels. In my experience getting the most performance out of gear such as the HP5370 requires attention to detail re signal levels and trigger set points. A selection of attenuators and a decent scope is helpful. I also found using the BVA as the clock source for the HP5370's was helpful (vs using the built in 10811's.) The prologix gpib to Ethernet adapters worked well for me. If I was doing it again on a budget for ham radio use: I'd probably still buy the G3RUH GPSDO, along with one other GPSDO. I'd probably pass on the HP5370 series counters and look for a used HP53132 counter and buy a dedicated frequency counter for measuring RF frequencies. (I have no personal experience yet with the HP 53132 but it seems to be well regarded.) I believe the HP5370's are getting a bit long in the tooth now. I bought four working used ones and now have two that are fully functional. I expect I could get at least one more working if tried. I also needed a special pulse generator for the alignment procedure. I picked up at least one of those as well. In hindsight I'd probably settle for a bit less performance in return for (hopefully) less hassle and buy newer Hp 53132's. Not sure I'd bother with the ocxo's, rb's etc until I had a definite need for that type of gear. Doubt I'd ever buy a BVA for amateur radio use but I believe a clean FTS1050 would be worthwhile if the price was right. (The packaging, battery backup system, external DC power inputs Etc.. has advantages in my view for Ham use.) I'd still want to setup some form of NTP server. All the usual cautions about buying used gear apply. Hope this is of some interesest. Others will likely have other opinions. All the best Mark S VE7AFZ Sent from my iPhone > On Dec 29, 2015, at 6:51 AM, Cash Olsen <[email protected]> wrote: > > Comments and critique are welcome and encouraged. Input for the actual > paper from HAMS and / or time-nuts regarding current projects will be much > appreciated. Time-nuts members might wish share personal anecdotes of how > they got started being a time-nut, or got started working with WWVB, GPS, > or GPSDO. Some of the old timers may remember the Shera project and can > share comments about it. > > I'd like to have inputs by this Thursday for final abstract submission > deadline on > Friday 1 January 2016. Presentation is in Albuquerque, NM on February 27, > 2016. > > DRAFT-DRAFT-DRAFT > > A High Quality Time and Frequency Laboratory on a Budget > By S. Cash Olsen KD5SSJ > > Following a brief retrospective look at time synchronization and frequency > syntonization by various methods, this paper will recall the seminal > publication of Brooks Shera W5OJM (SK) in QST magazine in 1998 which > introduced many amateurs to time and frequency measurement based on the > Global Positioning System (GPS). Low cost and high quality GNSS (Global > Navigational Satellite System, the USA DoD subset is GPS and will be used > generically in this paper) receivers have spawned many recent and current > projects by HAMS, world wide, to discipline both quartz and atomic > (rubidium) oscillators. With amateur projects as varied as weak signals > (such as QRSS, WSJT, EME) and microwave mountain topping to synthetic > aperture and steered arrays of antennas, frequency coordination and time > synchronization are of great importance to many Amateur Radio enthusiasts. > This paper will offer technical insight into the methods and techniques for > equipping a very high quality time and frequency laboratory on an amateur's > budget, approximately the cost of a used transceiver. Attention will be > given to the distinction between frequency (FLL) and phase (PLL) lock > loops, sawtooth correction of 1PPS signal from GPS, distribution of > reference oscillators and timing signals, Four Channel Dual Mixing methods, > Time Interval Counters, as well as, tips and tricks to maintain high > accuracy in measurements. Briefly, I will show how this subject speaks > directly to the charter of the Amateur Radio Service, Part 97.1 > (b)(c)(d)(e). > > DRAFT-DRAFT-DRAFT > > -- > S. Cash Olsen KD5SSJ > ARRL Technical Specialist > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
