We changed our privacy policy. Read more.
12

GPS-based frequency standards @larsks answer rightly pointed at devices that use GPS to generate the 1-second pulsing. That's the correct way to go. Curiously, these modules only address the once-per-second accuracy issue, not the frequency standard issue, which GPS is indeed commonly used to solve: You'll find a lot of modules on the market that will ...


12

In No WWVB? No problem!, KB6NU points at two projects that show you how to build your own low-powered WWVB-replacement to keep your clocks in sync: μWWVB: A Tiny WWVB Station. This project uses an attiny44 microcontroller and a USGlobalSat EM-506 GPS module to simulate WWVB. One Component Radio Clock Time Transmitter: This project uses an attiny45 ...


7

WWV and WWVH broadcast time and frequency reference information continuously, using AM on 2.5, 5, 10, 15 and 20 MHz, so you should be able to pick up all of them using your receiver, given an adequate antenna. At my location (San Francisco Bay Area) with lousy equipment, these signals are only slightly stronger than shortwave broadcast stations, but more ...


5

Given that I don't have a frequency standard or other known transmitter available, what is the easiest way to calibrate the NooElec NESDR SMArt which is using a TCXO rated at 0.5 PPM.? I.e. to determine the PPM calibration value? Find any continuous broadcast signal that has a carrier and you know the nominal frequency of, and adjust the PPM value until its ...


3

There are many ways you could calibrate. For measuring SWR, try this: Attach a 50Ω dummy load to your transmitter. The SWR should be 1:1. Then, attach two 50Ω dummy loads in parallel, giving you an effectively 25Ω load. The SWR should be 2. It seems you also want to measure power, and not just SWR. If you have some attenuators available, you can put them ...


3

Depends on your receiver sensitivity and antenna location. I've seen some many-decades-old portable shortwave radios pick up at least one WWV frequency using their simple built-in half-meter to meter long metal whip antenna.


3

I want to add some solutions to Kevins answer. Apparently I'm lucky to own the SMArt device as it is really stable with a PPM between 0.5 - 1.0 at all bands I've looked at. (Just as advertised.) So how do you calibrate your less stable RTL-SDR? Basically there are many different ways out there. The easiest is indeed what Kevin Reid posted, whose method is ...


3

Don't forget about CHU (and here is the official site) which is the Canadian equivalent to WWV. It's at lower power and it's not as well-located geographically (it's located near Ottawa), but it's receivable in most of the eastern US and increasingly less well as you head west. Here in VE5-land (Saskatchewan) I certainly receive it sometimes, but I also ...


2

However, depending on which options I choose on the Spectrum Analyzer, my measurements are different by up to 6-10 dB(!). Using a spectrum analyzer needs a bit of understanding what it does: it sweeps a filter across the spectrum and measures the power passing through that filter. I didn't know how to properly use a spectrum analyzer when I first did, and ...


2

Another great way to listen for signals, especially stronger ones, other than WWV and WWVH, is to find some active AM broadcast stations within the 1.8 to 30MHz range. Head over to this site http://www.short-wave.info/, and use the top most form, selecting any station, and preferred language, make sure NOW is checked, and hit GO! YOu can pretty much tune ...


2

In theory, if you can expose this device to a known field, you should be able to calculate some constants which allow you to convert the measured current (in μA) to a power density (in power per area, such as mW per cm2). Power is proportional to the square of current. T1 introduces some unknown gain, and the filters have some unknown loss. The antenna has ...


2

Seems like I was indeed wrong. The displayed trace displayed was Data/Memory (hence the /M in the top of the screenshot). After redoing the calibration and selecting Data for display, the unit is within +/- .04dB in the whole range. My mistake... Thanks to Default95401 on the Yahoo HP/Agilent test equipment group for pointing that out...


1

Mike Bryce covered a 3:1 dummy load in QST, in Feb 2013, this will NOT give you an accurate input power reading, but WILL generate a known SWR. The technique uses a 150 ohm resistive load creating an SWR of 3:1, with enough current/watt capacity, and an adequate heat-sink, so you do not overload the dummy load's thermal limits, when you transmit from the ...


1

An end-fed http://www.aa5tb.com/efha.html tuned for 2.5MHz will also serve well at the higher frequencies you seek.


1

Having built an HF receiver you should have little difficulty making a small crystal oscillator in a metal box. It is battery powered, oscillates at 1, 5 or 10 MHz and radiates only from a small stub antenna. Use it to test any HF receiver. The receiver will pick up the harmonics of the crystal frequency; thus you can both check both the receiver frequancy ...


Only top voted, non community-wiki answers of a minimum length are eligible