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Re: T41 LPF Options
¿ªÔÆÌåÓýThe SWR/Power bridge log-amp version is far more accurate than the diode version¡ and over a much wider power level.? So for example, the Log-amp version once calibrated (just a single point ¨C S11) gives accuracy of 1db over the entire 92 db power range (-75db to +17 db) of which we only use a fraction of that range¡ and that is over the entire frequency range of the log-amp (DC to 500 MHz). ? If you are fine with up to 20% error in the power reading (function of frequency and how good the diode is¡ you can use better diodes but experiment yourself to find the ones that work best.? Good RF diodes cost more but give better results and are more linear over the power and frequency range.? The 1N5711, BAT85, 1N34 etc. are reasonably good choices).? You are subject to the A/D range in the teensy and the way the power section transformer has been wound for attenuation of the RF signal.? That¡¯s still ok¡ lots of radios use this technique and give adequate results.? The equations to implement are simple.? The software guys can add them in easily. ? ? ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Jerry via groups.io
Sent: Wednesday, May 28, 2025 11:19 AM To: [email protected] Subject: [SoftwareControlledHamRadio] T41 LPF Options ? There is quite a difference in price in the Log Amp Detector and Diode Detector options. Before I chose the cheaper route, what is the performance difference I will see in the display and are both options now supported and selectable in the software? Also, the same question for the Digital Power report and the analog Power report options, what is the performance difference I will see in the display and are both options now supported and selectable in the software? Thanks, Jerry N KD4TNX |
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Re: T41 Hilbert Filter Design
Will you look at that, it works! I'll add support for this approach when I get to the transmit code rewrite.
On Wednesday, May 28th, 2025 at 11:10 AM, Bob Larkin <bob@...> wrote:
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T41 LPF Options
There is quite a difference in price in the Log Amp Detector and Diode Detector options. Before I chose the cheaper route, what is the performance difference I will see in the display and are both options now supported and selectable in the software?
Also, the same question for the Digital Power report and the analog Power report options, what is the performance difference I will see in the display and are both options now supported and selectable in the software?
Thanks,
Jerry N KD4TNX |
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Re: New SI5340-based RF Board in development
¿ªÔÆÌåÓýThat oscillator on a small daughter card would be a great way to try this and other oscillators like it. ? Also¡ I did finally find FFs that operate in the GHZ region.? I ordered a couple dozen so may try out the divide by N again¡ ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of John Bennett via groups.io
Sent: Monday, May 12, 2025 1:12 PM To: [email protected] Subject: [SoftwareControlledHamRadio] New SI5340-based RF Board in development ? In the spirit of posting efforts currently underway, I have been working on a new RF board and associated driver software. In a nutshell, the new board uses the Skyworks SI5340 instead of the SI5351. This change addresses several issues. The SI5340 offers rock solid performance from 100 KHz to 250 MHz with LVCMOS outputs (employed by the prototype RF board), dramatically reduced phase noise and jitter, much improved clock symmetry (upon which the performance of Tayloe mixers depends), and much simpler application-level control software (no mucking about with the PLL, Multisynth, or phase at the application level). The new RF board replaces the 5351 with the 5340, and restores true split operation (the SI5340 has four outputs, three of which are used for RX, TX, and CWTx). The most challenging part of the software was the algorithm for setting output frequency, that is, given a desired frequency, find near-optimal numerator and denominator values for the various dividers used within the SI5340. My software employs a mediant-based algorithm attributed (incorrectly) to Farey, and efficiently produces results comparable to those produced by ClockBuilder Pro (the stand-alone program for configuring Skyworks parts). Current status: 1) Driver and driver example code complete and tested with main board and SI5340 EVB 2) T41 software (forked from V66.9) patched to ifdef choice of SI5340 or SI5351 RF Board compiling and in test 3) New RF board hardware under construction (PCBs back from China; parts on hand) For the curious, prototype schematic and board pic are attached. 73, John Bennett AE0AM |
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Re: Strange 15 happenings
¿ªÔÆÌåÓýThat should have been 15M¡ ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of K9HZ
Sent: Tuesday, May 27, 2025 10:43 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Strange 15 happenings ? I have not looked at the code, but when we were all discussing the TX output calibration, we were going to have it set up BAND (that is, a different calibration constant for each band¡ this will be important once we get to 100W).? I think that¡¯s where the code ended up but if you didn¡¯t complete the TX calibration on 17M¡ no telling what the default calibration constant allows!? ? ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Tim via groups.io ? I was having fun working DX on 20 and 17M's today. Saw activity on 15, made a few calls noticed output in SSB was low. SWR was perfect (Steppir) so I decided to play with TX attenuation. Changed from 5 to 1. Display went wonkey on TX. Switched to CW and it stayed in CW after key up.? Went back 20m's all good, same with 17. Back to 15 and same conditions, ran out of time so I did not reboot and start over. Did see anything weird when doing TX calibration. Will do more testing tomorrow. Tim W4YN? ? |
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Re: Strange 15 happenings
¿ªÔÆÌåÓýI have not looked at the code, but when we were all discussing the TX output calibration, we were going to have it set up BAND (that is, a different calibration constant for each band¡ this will be important once we get to 100W).? I think that¡¯s where the code ended up but if you didn¡¯t complete the TX calibration on 17M¡ no telling what the default calibration constant allows!? ? ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Tim via groups.io
Sent: Tuesday, May 27, 2025 9:30 PM To: [email protected] Subject: [SoftwareControlledHamRadio] Strange 15 happenings ? I was having fun working DX on 20 and 17M's today. Saw activity on 15, made a few calls noticed output in SSB was low. SWR was perfect (Steppir) so I decided to play with TX attenuation. Changed from 5 to 1. Display went wonkey on TX. Switched to CW and it stayed in CW after key up.? Went back 20m's all good, same with 17. Back to 15 and same conditions, ran out of time so I did not reboot and start over. Did see anything weird when doing TX calibration. Will do more testing tomorrow. Tim W4YN? ? |
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Re: MF changes
¿ªÔÆÌåÓýOh!? Well PLEASE keep us up to date! ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Rob G7WKE via groups.io
Sent: Tuesday, May 27, 2025 4:10 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] MF changes ? ? Hi Bill, I'm just about to start populating a Main board that has the SGTL5000 and the SPI driver onboard. I've also done away with the 3.5mm Jacks and replaced them with JST connectors, along with moving the regulators and the shutdown circuitry to a separate PS board. I've no idea if it'll all work out, but that's the beauty of being able to experiment and do your own thing! ? Rob G7WKE
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Re: MF changes
¿ªÔÆÌåÓýThe oscillator could be anything you want to put on that oscillator board. ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Tim via groups.io
Sent: Tuesday, May 27, 2025 10:48 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] MF changes ? I would be in for some pre-populated boards to play with.? and eliminating the issue with audio hat would be much appreciated (caused me a lot of headaches!)? as to plug in oscillator board would it accmmodate the TXOC also as an option also?? Tim W4YN |
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Re: T41 Hilbert Filter Design
To clarify: in the 90/0 degree case, you still need to pass the data through the "0 degree" filter.? Every FIR filter will impart a phase shift that increases linearly with frequency [will come back to this later and address the constant delay question]. The absolute phase shift for the "0 degree" filter looks like this: That's a lot of degrees! However, the filter design process allows you to add an extra phase shift that is constant with frequency. So we can make a second filter that has an extra 90 degrees of phase shift added such that the phase difference between the two filters is a constant 90 degrees: If I subtract the black curve from the red curve to get the relative phase shift between these two filters I get the plot I shared earlier: So in summary, 90/0 doesn't refer to the absolute phase shift of the filter -- it refers to the extra phase offsets that we added to FIR filters. Rather than choosing +90 and 0, we could choose +45 and -45. Or 0 and -90. Or 153 and 63. What matters is the phase difference between the two filters. As Bob points out, since the phase shift through the 0 degree filter has a linear slope, can we just shift the samples in time instead, since a constant time shift equates to a phase shift that increases linearly with frequency? (Maybe you meant something different Bob, apologies if I misunderstood you). Since this is a digital system, we're limited to delays that are a multiple of the sample rate. Assume we shift the time earlier by 10 samples. The sample rate is 24 ksps, so this equates to a time shift of -10/24000 seconds. For a signal at frequency f, this time shift corresponds to a phase shift of: 2*pi*(-10/24000)/(1/f) If we look at our "0" degree filter, the delay we need to produce the same phase shift with frequency falls between 49 and 50 samples when sampled at 24000 ksps. That won't work. What if we perform the delay before the decimation step? Each time step is 1/8 of the time, so we should be able to get closer to the perfect value. And we do, but still not close enough: So in conclusion we can't get away with this shortcut, unless we can shift the data by half a sample (a delay of 49.5 samples is perfect). What do you all think -- am I thinking about this right?
On Tuesday, May 27th, 2025 at 12:49 PM, Bob Larkin <bob@...> wrote:
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K9HZ
Jerry