Firmware patch for Kenwood TS-950SDX HiFi AM mode available

[BillPaul]

Well, I've thought about it, I've talked about it, and now I've gone and done it. With help from da VooDoo crew, some elbow grease and a bunch of trial and error, I've managed to patch the firmware for the Kenwood TS-950SDX to correct the famous "AM doesn't work in HiFi mode" problem. I finally got the code modified just right and tested it just last night -- it ended up working perfectly. The radio's behavior is completely unchanged, except now it transmits in AM when the LPF is set to "off" without needing any manual jiggery pokery or the off-board computer assist program that I wrote.

I now have the only TS-950SDX in the world where the statement that "voodoo audio won't work on AM" is 100% untrue.

So without further ado, here it is. If you have access to an EPROM programmer and want to try the patched firmware yourself, you can download it from here:

http://people.freebsd.org/~wpaul/ts-950 ... patch.html

The main CPU in the TS-950SDX is an NEC uPD7810. It's a relative of the Zilog Z80. I managed to disassemble the firmware and modified it to work around the glitch in the DSP unit's gate array which prevents AM from working in HiFi mode. The ZIP file provided on the page mentioned above contains technical details about how the modification works. The patch is based on the most recent firmware available for the TS-950SDX, version JQGA, so you get the benefit of all Kenwood-supplied firmware bug fixes too. Both the original unmodified firmware image and the patched image are included.

If you don't want to change your radio at all, you can still use the off-board CAT program, which is still available here:

http://people.freebsd.org/~wpaul/ts-950 ... m_cat.html

So now there's not one, but two ways to do HiFi AM with your TS-950SDX. How's that for a bargain! For simplicity, both pages can be accessed from here -- just name your poison:

http://people.freebsd.org/~wpaul/ts-950sdx/am_dsp

I want to thank the VooDoo Guru for his help, because without his assistance this wouldn't have been possible. (Or at the very least, it would have taken much longer.)

As with the CAT program that I wrote, the author disclaims any liability for damages resulting from use of this code. If it breaks, you get to keep both pieces.

If anyone has any questions or comments, please let me know. I'm not expecting to have to update the firmware again, but if so I'll keep ya posted.

Share and enjoy!

-Bill

[Voodoo Guru]

Howdy BillPaul,

WOW...
It is the innovation and tenacity of people like you that put us in awe. The AM Transmit Bandwidth/Quality of the SDX was it's great Bane. Your talent, experience, and knowledge has made the TS-950SDX even that much more 'Over the Top' then any other radio. With your newly re-coded Firmware, no longer will the SDX have to sit among the 'Ho-Hum' Low Level Modulated AM Transmitters of the Amateur Radio world. It can now rise up and takes its proper place among the stellar performers.

We were glad to assist you with the DSP/Gate Array Coding Data for this fine accomplishment. No doubt you could have retrieved it on your own, but its always nice when you can have the information you need already decoded and available. This no doubt saved you some time. We here at Voodoo-LABS are ecstatic to have played a part in your accomplishment, even if it is a small part.

Since you are now probably the only person on this planet (other then the original Japanese engineer) that knows the SDX Firmware Coding, we have upgraded your Forum Rank Title to reflect this. You will now be immortalized on this forum as the 'Digital Voodoo Guru'. This Rank Title will appear underneath your User Name on all posts.

We have also made your post 'Sticky' and it will now remain at the top of the Topic List.

When we have time, your accomplishment will also be reflected on the Voodoo-LABS website.

Bill,
Thanks again for your wonderful contribution, not only to this fine hobby, but to the furthered evolution of the TS-950sdx.

Take Care,

[BillPaul]

Just a quick node:

I've made a minor update to the modified firmware. The basic operation of the patch is to modify the code that sends commands to the DSP: when sending the command for HiFi AM mode, the patch causes the main CPU to first send a normal AM command (LPF set to 3100Hz) and then sends another command for HiFi AM (LPF set to off). The previous version of the patch would send both command words back-to-back in quick succession. The updated version inserts a few microseconds of delay between them. This delay is short enough that it's completely imperceptible to the user.

This was done for the benefit of a project that the mad scientists at VooDoo Labs are working on. (I'm not at liberty to say what it is yet, but it sounds exciting.) As far as the radio is concerned, either version works just as well, but I wanted to avoid any potential conflicts between my modded firmware and the VooDoo Labs work. With the added delay, both should work together seamlessly.

Anyway, the zip file referenced at the link in my original post has now been updated with the new patched firmware image and disassembly file. I don't know if anyone's actually made their own replacement EPROM with the patch yet, but if you have, and if you want to upgrade, it should be trivial to erase and reprogram your EPROM chip. (If you used a one-time programmable device though, you're out of luck. Sorry about that. )

-Bill