Skyscan atomic clock model 88202cop generator#
Skyscan atomic clock model 88202cop portable#
Skyscan atomic clock model 88202cop code#
Skyscan atomic clock model 88202cop Pc#

It has only an 8-line by 40 character display and 32k of RAM and a CMOS 8085 processor that runs at less than 4 MHz, but it has a built-in clock which, by the way, is not Y2k compliant as it has a hard-coded '19' in mask ROM for the first two digits of the year! By knocking together a simple program in the computer's built-in BASIC language I could fairly easily generate a time code that was timed using the Model 100's internal clock. Made in about 1983, this thing has been around for a long time.

In the end, I settled on something much more retro and comparatively low-tech: An old Radio Shack Model 100 Laptop.

Skyscan atomic clock model 88202cop Pc#

In thinking about this, all sorts of things came to mind from hacking a program with a Raspberry Pi to 'key' the 60 kHz signal to programming a PIC with an attached GPS receiver to generate a modifiable time code to even using a PC to toggle some sort of hardware line. The next step was to generate some time code.

Skyscan atomic clock model 88202cop portable#

Connecting the output (DC) terminals of this full-wave rectifier to a couple meters of wire I now had a coil that I could wrap around the clocks being tested to induce into them a 60 kHz signal: A quick test with a portable ultrasonic receiver and coupling loop that I have used in the past to listen for WWVB and other longwave signals verified that this portion was working properly.

Skyscan atomic clock model 88202cop generator#

Rummaging around, I found a small-ish (4 amp) bridge rectifier (but I could have used 4 ordinary diodes) and in testing it with an oscilloscope, noted that its diodes were plenty fast enough to take the 30 kHz sine wave from the audio generator and produce a nice, pulsating DC 60 kHz waveform out the other end. Setup for simulating the WWVB signal using a computer-controlled relay (in the Model 100),Ī 30 kHz signal source and a full-wave bridge rectifier. That's what full-wave bridge rectifiers are for! Since this audio generator could produce about 5 volts (at 600 ohms impedance) of nice, stable audio signal at 30 kHz I just needed to double the frequency. Frequency stability is important as the bandwidth of these receivers is just a few Hertz and not only would it be rather tricky to set a free-running oscillator exactly on-frequency, it would also be unrealistic to expect it to stay within +/- 1 or 2 Hz over a period of several days without a bit of extra care. Since the suspicion based on the previous observations was that it seemed more likely that these clocks were 'unhappy' with the date with which they were presented and were subsequently unable to set themselves to the correct time, I decided to generate my own local version of the WWVB 60 kHz signal to test this theory.įor a signal source I didn't have handy a synthesized 60 kHz generator (I could have built one, though) but I did have a synthesized audio generator built into a service monitor that could produce a 30 kHz sine wave. The NIST is NOT responsible for this clock's The Augpost - linked here - discusses the construction of an active 'repeater' to relay signals from an outdoor antenna to indoor clocks so that they may reliably receive the signal from an LF time station such as WWVB - but it will NOT solve the problem with the affected clocks! If your clock will properly set itself ONCE after removing the battery and replacing it - but it does NOT set itself again, despite the 'antenna' symbol, it is a defect in the clock itself! Because the affected clocks are rather old, it is perhaps unreasonable to expect the manufacturer to 'make good' on the clocks' defects, but I would expect that they do know by now the true nature of the defect and would post information accordingly.Ĭomment: This problem may also affect Skyscan models 8675 as well. PLEASE NOTE: There have been anecdotal reports by some customers of the affected-model clocks that some representatives of the manufacturer suggest that they are misconfiguring them and/or a change in WWVB's signal format is to blame for their clock no longer working. In a previous post - link I commented on how several radio-controlled clocks of one particular model (Skyscan model 86715) seemed to have stopped working properly in the summer/fall of 2012 in that they would synchronize to the proper time and date only once - just after the battery had been installed - but never again.