VK4ZXI

Why the phase noise of a U-Blox GPS module at 10 MHz is terrible. There was a YouTube video showing the poor phase noise of a U-Blox GNSS module programmable pulse output at 10 MHz but cleaner at 8 MHz. It suggested that it was because the module does an integer division of its disciplined clock at 24 MHz. So the 8 MHz is clean and the 10 MHz is not. https://www.youtube.com/watch?v=M6SmdqMA-Dg&t=1611s  "Using a GPS module as variable frequency reference standard" In a U-Blox application note, I found that the presenter is correct in that it uses an integer division, but the clock is 48 MHz. The non-integer pulses seem to be made up of two pulses with a delay between them to give the correct frequency pulse but with many artifacts and consequent phase noise, as shown in the image from the paper. https://content.u-blox.com/sites/default/files/products/documents/Timing_AppNote_%28GPS.G6-X-11007%29.pdf   "GPS-based Timing Considerations with  u-blox 6 GPS receivers"

 Have PN2060A phase noise analyser, will measure! This post is for measurements of different TCXOs I have on hand. The measurements are not too exact as I am not set up for precise measurements. However, the two reference TCXOs run on batteries and all the equipment is warmed up for at least 30 minutes. If I see an odd result I repeat it. Before I start, the performance of the latest R&S FSPN phase noise analyser for comparison. Its noise floor is a bit lower. The plot is processed data with spikes removed, among other things, so comparable to the PN2060A data after Matlab processing. One thing R&S stress is improved DC supplies, showing the sensitivity to power supply noise. Hence, running everything on batteries is a good idea as a cheap alternative. The floor of the instrument is about 180 dBC/Hz. This is just above the noise from a resistor os about 184 dBC/Hz, the absolute floor. Keysight MXA N9020A Vector signal analyser.  As the N9020A is for analysing digital modulation

  An economical way to measure phase noise using the PN2060A cross-correlation Phase Noise Analyzer  Six weeks ago, I had heard of the phase noise of an oscillator but didn't really know what it was, much less how to measure it. In a short space of time, courtesy of Google and Youtube, I now know what it is, how to measure it and can measure it with an inexpensive phase noise analyser. In this post: 1 A brief summary of phase noise and how it is measured. 2 An overview of the PN2060A Phase Noise Analyzer, a low-cost instrument (US$480) available directly from Yanjun Ma BG6KHC in China, The instrument is a work in progress with new models available soon, but at a higher cost. 3 Using the PN2060A Phase Noise Analyzer to measure the phase noise of two modern spectrum analysers' reference 10 MHz and a CTI OCXO. All very easy after a couple of small hiccups as noted. In conclusion, the PN2060A Phase Noise Analyzer is an excellent, low-cost and easy-to-use instrument. What is phase n

  Measuring phase noise https://edadocs.software.keysight.com/kkbopen/measuring-phase-noise-with-a-real-time-sampling-oscilloscope-584447063.html

 Tinkering with a mobile/cell phone repeater booster, very high-tech RF. I have been tinkering with improving mobile phone reception in remote areas (or buildings that have poor phone reception). There are two main ways to do it. First, an external antenna is mounted on the vehicle with a cable to an internal antenna in a phone cradle. The external antenna is much better than the phone antenna and away from the car shielding. I have this system installed in our camper and it worked very well on our trip to Winton in outback Qld. My mobile is one bar better than my friend's phone. Cost~$400 plus fitting. Second, as above but with a booster. The booster is a bidirectional amplifier with additional filtering. The boosters are carrier specific, so always use a Telstra one for remote areas. The boosters allow all phones to use them. There is a teardown of one of these, see below and they are very sophisticated. I have been playing with one with my test gear just to see how they work. Am

  Rigol RSA-3015N 9kHz TO 1.5GHz REAL-TIME spectrum analyser WITH VNA https://emona.com.au/products/electronic-test-measure/rf-test-equipment/rsa-3015n.html GCARS repeater UHF Band Pass / Band Reject Duplexer for CB repeaters https://www.rfi.com.au/core/media/media.nl?id=3987315&c=3389566&h=7HxM371SKCIoQI4SUAQLjS9xWxD_rP8Cc1u2S02y8vj3Fszl Understanding Hybrid-Filter Transmitter Combiners https://emrcorp.com/understanding-hybrid-filter-transmitter-combiners/ https://emrcorp.com/wp-content/uploads/2022/07/EMR-hybrid-combiner-manual.pdf RFI Hybrid Coupler, 4 Port ,3dB 380-550MHz ,200W; N(F) https://www.rfi.com.au/SP3855-2203-11 https://www.repeater-builder.com/antenna/ant-sys-index.html#combiner RFI Single Circulator 440-480MHz; Symmetry, N(F) https://www.rfi.com.au/SP4448-3100-11 Ferrite Isolators or Circulators Characteristics and Uses https://www.youtube.com/watch?v=-J8eDdwHf-0 LNA for use with splitters https://www.minikits.com.au/electronic-kits/rf-amplifiers/rf-low-noise/PGA