WWV TRF Receivers

wa8pyr

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Does anyone know where I can purchase a receiver like the one in this site:

Those are project radios designed by a ham radio operator and written up for QST magazine. If any are being built and offered for sale it would probably be noted in the article somewhere. If not try contacting the author; his contact info is at the end of the article.
 

a417

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That was meant to be built, don't think it can be purchased in a brick & mortar store. The BOM & schematic are in the PDF, so it's meant to be done by the reader. I don't currently see any on ebay, but you might be able to convince someone to build it for you (if you are not comfortable with basic soldering) although they would be setting the price on you.

[edit - tom, you won!]
 

chapi

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What I like about this device is that it's possible to see the carrier wave form on the scope.

I tried it with few receivers but was successful only with crystal radio. Ideally I would want to view on the scope the wave form of a carrier wave from a distanced satellite like noaa 17 or sirius xm radio, but local radio stations will be alright too. Any ideas how to do it? Any receiver has a built in rf out jack?
 

majoco

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The whole idea of a TRF is that there is no frequency changer in the receiver to modify the received signal frequency - trying to receive directly from a satellite would be very tricky - the low noise amplifier frequency changer box right up at the dish is there for a reason!
 

chapi

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"trying to receive directly from a satellite would be very tricky"

Any one knows what is the trick?

I prefer satellite, but any receiver which once connected to a scope will display the carrier wave from a distanced transmitter will do.
 

wa8pyr

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The whole idea of a TRF is that there is no frequency changer in the receiver to modify the received signal frequency - trying to receive directly from a satellite would be very tricky - the low noise amplifier frequency changer box right up at the dish is there for a reason!
"trying to receive directly from a satellite would be very tricky"

Any one knows what is the trick?

I prefer satellite, but any receiver which once connected to a scope will display the carrier wave from a distanced transmitter will do.
These receivers aren't intended for satellite reception; they're intended for use receiving WWV transmissions on 5 and 10 MHz to use for calibrating other equipment.
 

wgbecks

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Chapi,

If you end goal is as a calibration refernce then you'll not get great results due to doppler shift caused by ionoshperic propagaion effects. You'd be way better off picking up a realitively inexpensive GPSDO.

Bill (WA8WG)
 

majoco

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Tricky bit 1 - the frequency....

GPS L1 Band:
1575.42 MHz with a bandwidth of 15.345 MHz
GPS L2 Band: 1227.6 MHz with a bandwidth of 11 MHz
GPS L5 Band: 1176.45 MHz with a bandwidth of 12.5 MHz

Narrow bandwidth is probably do-able, but 11MHz????

Tricky bit 2 - the signal level is below the noise.

In the frequency allocation filing the L1 C/A power is listed as 25.6 Watts. The Antenna gain is listed at 13 dBi. Thus, based on the frequency allocation filing, the power would be about 500 Watts ERP (27 dBW).
Now, the free space path loss from 21000 km is about 182 dB. Take the 500 Watts (27 dBW) and subtract the free space path loss (27 - 182) and you get -155 dBW. The end of life spec is -160 dBW, which leaves a 5 dB margin.
-155dBW is -125dBm which is just a bit over 0.1uV in 50 ohms.


Tricky bit 3 - because the signal is repetitive, you can use coherent detection methods to dig it out of the noise, so.... briefly....


So, in reality, all this is far above my pay scale.

My grandson asked me "how does the GPS know where we are?" - even that's a tricky question to answer to an eleven-year old who is still grappling with the speed of radio waves and time.....but in the end we worked it out as a distance from at least three satellites.
 
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chapi

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Thanks, I watched the GPS video, but I don't think the wave form on the scope (around 6:32) is of the GPS satellite's carrier wave, which is what I'm after..
 

wa8pyr

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Chapi,

If you end goal is as a calibration refernce then you'll not get great results due to doppler shift caused by ionoshperic propagaion effects. You'd be way better off picking up a realitively inexpensive GPSDO.
Another alternative is a 5 or 10 MHz oscillator; I've seen a number of high-performance units on eBay. Probably a better way to go for calibration anyway....

For example: McCoy Ovenized 10 MHz Oscillator OCXO 12 VDC Sine Wave Output OSC92-100B | eBay
 

chapi

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"That was meant to be built, don't think it can be purchased in a brick & mortar store. The BOM & schematic are in the PDF, so it's meant to be done by the reader. I don't currently see any on ebay, but you might be able to convince someone to build it for you (if you are not comfortable with basic soldering) although they would be setting the price on you".

Any one knows who may built it for me?

Another question. If I have 2 of those receivers connected to 2 channels of the scope, one for each, I would be seeing 2 10mhz wave forms on the scope I believe.

Now, if I'll move the antenna of the receiver which is connected to channel B of the scope, would the wave form on the scope move too?

The rational is this: Rf moves at a speed of about 1' per nanosecond. In the youtube the time scale on the scope is 100 ns.


Thus, for every feet I'll move the antenna away or toward the rf source (wwv station or the the reflection's point), the wave form will move 1ns too.

What do you think?
 

wd8dsb

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Chapi,

If you end goal is as a calibration refernce then you'll not get great results due to doppler shift caused by ionoshperic propagaion effects. You'd be way better off picking up a realitively inexpensive GPSDO.

Bill (WA8WG)
Hi Bill, I'm the designer of the WWV TRF receiver being discussed, and I would like to make a few comments. With a GPSDO you really have no idea if its output is accurate or not since firmware and hardware is involved to generate the GPSDO output from the received GPS signals and unless the specific model of GPSDO you are using has had its output validated against a NIST traceable standard you really don't know if the output signal of your GPSDO is accurate or not even if it is very stable (hopefully the manufacturers of each model of GPSDO do in fact validate the output of their GPSDO against a NIST traceable standard). The beauty of the WWV TRF receiver is that there is no firmware or hardware frequency conversion involved, so the output of the WWV TRF receiver is directly traceable to NIST but the accuracy is dependent on doppler shift as you mentioned. Due to doppler shift the WWV TRF receiver accuracy is typically +/- 0.2 Hz or better during the middle of the day when the ionosphere is most stable versus at sunrise or sunset. Therefore if you are looking for a frequency refererence directly traceable to NIST the WWV TRF receiver fits the bill and there is no need to have it periodically checked against a NIST traceable frequency reference to make sure it's still working properly, etc. In reality I think GPSDO receivers are a great tool (and very accurate), but you are indeed trusting that it's designed properly in the first place to produce accurate results, and you are also trusting that it continues to function properly. Bottom line is if you are looking for a frequency reference directly traceable to NIST that's accurate to within 1 Hz, the WWV TRF receiver is hard to beat. 73, Don (wd8dsb)
 

chapi

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encino, ca
GPSDO will not work for my purpose any way I believe, due to multiple satellites. I need to know the location of the rf source.

Aaron D. Parks:


agreed that moving one antenna in a two receivers setup that each of them connected to a scope channel, the wave form on the scope will move about 1ns for each 1' the antenna is moving, but like Don, he also could not built those receivers for me. I'm waiting now for a trf kit to arrive any day for 3Mhz stations, but would rather use wwv trf receivers. If any one reading believe he may do the job or knows someone who may do it please let me know, I will pay the cost of the receivers of course.
 
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