Microwave Frequency Standards
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Transcript Microwave Frequency Standards
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Texas
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Microwave
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Microwave
Frequency Standard
Jim Hudson
WA5JAT
HamCom
June 2010
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Microwave
Frequency Standard
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• Why Do we Need a Frequency Standard?
•Remember the 100 KHz Calibrators on HF?
•The Same Issues Exist on the Microwave Bands
•Uncertainty in Frequency (+/-100 KHz at 24 GHz)
•High Gain Antennas for Microwave Bands
•<3 Degree Beam Width
•Uncertain Rover Station Locations
•Too Many Things to Monitor:
•Antenna Elevation/Azimuth
•Frequency Dial + Readout
•“Hopefully”, Copy a CW Signal “In The Noise”
Doing All These at Once is “Not Fun”
Having a Precision Frequency Standard and
Eliminating the Frequency Uncertainty is a BIG Help
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Frequency Standard
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Surplus Equipment is Available!!!
RFG-M-RB & RFG-M-XO
(EFRATOM Labels on PCBs / LUCENT on Panel)
Rubidium Std
RFG-M-RB
Crystal Oscillator
RFG-M-XO
Rubidium Std (RB) outputs to XO which locks to the RB
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RFG-M-RB
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Texas
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These Screws Release
the Rb unit from the tray
15 MHz Output
10 MHz Output
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P1 = DB9 Male Power Connector
Pin 1 = +24 VDC
Pin 2 = Common
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Frequency Standard
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RFG-M-RB
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Rear Panel Removed
Rubidium Std
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House Keeping Sub-Unit
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Frequency Standard
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RFG-M-RB
These Screws Release
the RB Sub-unit after
Rear panel removal
The RB Sub-Unit Slides Sidewise and Unplugs
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Frequency Standard
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LPRO-101
10 MHz
Sine Output
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Frequency Standard
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Supplier Specification Sheet
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Source: http://www.datasheetarchive.com/
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Comparison of Several Frequency Sources
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Source: http://www.leapsecond.com/museum/manyadev.gif
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Frequency Standard
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Comparison of Several Rubidium Sources
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Source: http://www.leapsecond.com/museum/lpro/
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Frequency Standard
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How Do You Use 10 MHz for a Microwave Frequency Standard?
•Direct Digital Synthesis (DDS)
•Phase Locked Loop
Followed by Multipliers to the Band of Interest
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Direct Digital Synthesis (DDS)
10 MHz In – 96 MHz Output
Source: NTMS FEEDPOINT Vol. 21, Issue 2 / WW2R
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Frequency Standard
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Microwave
Phase Lock Loop (N5AC/Down East Microwave)
10 MHz in - 1152 MHz Output (And 49 Others Available)
Society
Frequency
Selection
Jumpers
Source: http://www.downeastmicrowave.com/PDF/A32_pd.pdf
Also See: http://www.n5ac.com/apolLO-32Operation.pdf
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Frequency Standard
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Example of a Frequency Multiplier
Source: http://www.w1ghz.org/MBT/multiband.htm
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Questions?
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RFG-M-XO
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Front View
Back View (Rear Panel Removed)
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Frequency Standard
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RFG-M-XO
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Top View
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Frequency Standard
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RFG-M-XO
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Bottom View
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Internet Search Came Up with:
]> To: "Discussion of precise time and frequency measurement" <[email protected]
Sent: Friday, December 29, 2006 6:44 AM Subject: Re: [time-nuts] Lucent RFG-M-RG and XO
> Back when these Lucent units were first appearing GPS had not yet been
> implemented at the cell sites here in Alaska. The rubidium was too noisy
> for direct frequency synthesis, so the XO unit was phase locked to the rubidium
> to provide the long-term stability needed, and the XO output was
> up-converted for the system clock. By using the XO to smooth the rubidium
> output the phase noise in the system clock was reduced due to better
> short-term stability in the XO. As I remember it (It's been a while) the
> 10M Rb disciplined the 10M XO, which was divided by 2, multiplied by 3,
> filtered, and supplied as the 15M system clock. The XO was always
> supplying the 15M system clock, and "standby" just meant the XO was locked to the
> rubidium, which was acting as the primary frequency reference. When the
> rubidium failed the system alarm output went high, XO PLL went into hold,
> the standby light on the XO extinguished, and the undisciplined XO became
> the source until the rubidium could be replaced. The GPS connection didn't
> appear until later units and disciplined the XO during normal operation,
> with failover on extended GPS loss to disciplining the XO from the
> rubidium.
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Internet Search Also Came Up with:
Sent: Monday, October 31, 2005 4:56 PM Subject: Re: [time-nuts] Unknown Efratom 10MHz Assy, information asked
> The board you are describing is used in the Lucent RFG-M-XO reference
> frequency generator. It takes in 10 MHz on J2 from a Rubidium oscillator and
> disciplines the Efratom SC cut OCXO on the main board from the 10 MHz input.
> The output from the OCXO is converted to 15 MHz and supplied as the
reference output on J4.
> The RFG-M-RB and RFG-M-XO normally mount together in a chassis (which I didn’t
> get) and the modules are connected to the chassis by a harness with a
> DB15 on the chassis end. The pin out for the harness is as follows:
> DB15M
TO/Pin#
Description
> Pin #
>1
RFG0 - P1-1
+24v 1.3A/0.6A
>2
RFG0 - P1-2
Common
>3
RFG1 - P1-1
+24v 0.6A/0.4A
>4
RFG1 - P1-2
Common
> 10
RFG0 - J3-1
Alarm
> 11
RFG0 - J3-2
Alarm
> 12
RFG1 - J3-1
Alarm
> 13
RFG1 - J3-2
Alarm
> > A second interface cable ties the RB to the XO as follows:
> RBJ5
XOJ5
> Pin #
Pin#
> 1
5
> 3
3
> > The male DB9 is P1 and pin 1 = +24v @ 400ma, Pin 2 = Common. This will power
> up the board so you can verify operation of the OCXO. Unfortunately that is
> all the information I have on the unit.
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Internet Search Also Came Up with:
Repair of Rubidium Source
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Author, G Molenkamp,
( [email protected])
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Frequency Standard
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Repair of Rubidium Source-Cont’d
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Frequency Standard
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Repair of Rubidium Source-Cont’d
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