Having developed several systems based on this principle, I am now pleased to offer the design illustrated on this page which incorporates the best results of my experience of the Jupiter GPS engine, phase-locked loops and OCXOs. With careful choice of components, patient sourcing and rational design I have been able to keep the price at level affordable by the small commercial or home laboratory and by serious radio amateurs. Read an independent comparison of several GPSDOs.
The frequency accuracy is of course set by the GPS idiom, and is essentially exact for practical purposes. The stability as given by the Allan Deviation is typically 5x10-12 at τ=10s. That figure is 0.05 Hz at 10 GHz and is a remarkably small value.
The low phase noise from the Axtal AXIOM40 OCXO results in a very clean 'sound' to harmonics in the microwave region, and with a power consumption of 300 mA at 12.5V this GPSDO is suitable for field operation from a car battery.
Other applications include radio beacon synthesisers, harmonic markers, 1 MHz 'comb' generators, downconverters, test equipment external frequency reference, small laboratory frequency standard.
Power Input Voltage minimum: 7.5V DC stabilised recommended: 12.5V DC stabilised maximum: 18.0V DC Current min: 0.3A max: 0.5A during OCXO warm up (about 2-3 minutes) Connector: Screw terminal block GPS Receiver Rockwell Jupiter TU30-D140-221 GPS connector: SMA socket Option: MCX socket. (No cost). Socket powered 5V for active antenna (100 mA, with short circuit protection) LED shows 1PPS (1 pulse-per-second); synced to UTC when receiver locked Signal Output 10 MHz sinewave, AC coupled Level: 13 dBm into 50Ω ; 1V RMS Connector: BNC Option: Output HCMOS/TTL 5V. (No cost). Option: Output HCMOS/TTL AC coupled ±2.5V square-wave. (No cost) (Options are alternatives to the regular items). Data Input/Output RS-232 in/out of GPS receiver Protocol: NMEA (user changeable to Rockwell binary) 1PPS on DCD line Connector: DE9S Warm-up Accuracy After 30 minutes < 10-10 typical After 60 minutes < 10-11 RMS accuracy (over a 10s period) 8x10-12 ; that is, 99% of measurements would fall within ±2x10-11 Stability (Allan deviation) typical 1s < 2x10-12 1000s < 2x10-12 10s < 5x10-12 10000s < 3x10-13 100s < 5x10-12 1 day < 5x10-14 Dimensions 35 H x 92 D x 150 W mm including mounting flange Weight 0.430 kg - Supplied with 80cm power cable with 6mm spade terminations. - Full documentation. - Built, tested and ready to use (that is, not a kit). Just connect your GPS antenna, apply 12V DC power and you're in business.
The price of this GPSDO and shipping is:
OCXO-based GPSDO, part No. 0091-000 £260 Shipping by secure service: UK £10 (Royal Mail SD) EU/US/AUS etc £17 (Insured air-mail) Shipping via Fedex, at cost; £30-£62 (please ask for specific quotation).
Kindly note that I am unable to supply power supplies or kits of parts for this product.
To order please send me an email; the address is just below. It's a graphic (to deter spambots).
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Frequently asked Questions
Prior GPSDO developments with emphasis on self-construction.
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Last updated: 2015 Aug 25