Competition for Pure Signal ?

w4bf
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Competition for Pure Signal ?

Postby w4bf » Tue Aug 23, 2022 12:49 pm

Ads for the new Icom PW-2 1 KW amp say it has linearization when used with ICOM 7610 HF radio. They show IMD improvements similar to Pure Signal. Does not appear to use RF feedback, the block diagram shows an FPGA at input of the amp.

Anyone with more info on how they are doing this?

https://www.ab4oj.com/icom/pw2/ic_pw2_ham_fair_2022.pdf
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w-u-2-o
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Re: Competition for Pure Signal ?

Postby w-u-2-o » Tue Aug 23, 2022 2:25 pm

Consider the following wild conjecture, after looking at the link and watching the Youtube video (linked below).

First and foremost, since the linearity measurements are most likely being made internal to the amplifier, only the PW2 can be linearized and not any part of the 7610 signal chain.

One might guess that predistortion data could be sent in an analog fashion back to the 7610 via the ALC connection. Or, perhaps the amp transmits some sort of correction table back to the 7610 over Ethernet.

The amount of improvement shown in the brochure is a bit odd. If one assumes that the graph scales are the quite common 10dB/division, then in the un-linearized state the amp would not meet USC 47CFR97.317(a)(1), which requires spurious to be -43dBc. Of course most amp's don't meet that, so I don't know how any of them are actually sold in the US but, still, it's a concern. In the linearized state it shows a quite respectable performance of -50dBc. Perhaps the performance graph for un-linearized has been "adjusted" by the marketing team. If it was closer to the -35dBc we normally see from these things, or even a legit -43dBc, the additional 7 or 15dB of performance achieved is within reason for only linearizing the amp and not the transceiver.

It seems unlikely Icom sees Apache or the openHPSDR community as any sort of competitor, at least I don't think that's what is driving them to add linearization. This whole thing is really a huge shot across Flex's bow. They did a fine job of toppling the entire market where entry level, direct-sampling SDR is concerned. Now they probably want to topple Flex's dominance in the contester market, and the features of this new amplifier go a long way towards doing exactly that. The linearization is just the cherry on top, Icom's way of thumbing their nose at their competitors. Icom was first with a direct sampling SDR among the Big Three and, surprisingly, Elecraft. Now they are first again and add Flex to that list. They know nobody else except Elecraft has a prayer of adding linearization without producing a whole new radio, so they will be enjoying that cherry for a long time.

At any rate it will sure be interesting to find out how it really works, and how well it really works. Now if Icom would only get off their high horse and allow a transmit passband greater than 3KHz they'd own the ESSB market, too.

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Re: Competition for Pure Signal ?

Postby K1LSB » Tue Aug 23, 2022 6:11 pm

Flex has been dangling the pre-distortion carrot for over eight years:

https://community.flexradio.com/discuss ... distortion

They said at that time they already had the requisite feedback loop implemented internally in their 6000-series radios. I saw that conversation and decided to take the plunge and purchase a Flex based at least partly on that premise/promise. Sadly, eight years later the dream of Flex pre-distortion is still only a pipe-dream. For that and other reasons I've long since divested myself of anything connected with the name "Flex".

The blurb in Icom's pdf states that "the technology corrects the signal distortion from the IC-PW2, by applying inverse distortion to the output signal [emphasis mine] from the IC-7610 exciter in advance", implying there's no correction applied by the amp to the 7610's signal prior to delivery to the amp.

With that said, I've observed that the Icom 7300 and 7610 have the cleanest and sharpest-shouldered transmitted SSB signals I've ever observed on my panafall (with the exception of another Anan). I've even remarked on that fact over the air and was told (though I haven't verified the accuracy of the claim) that Icom does in fact employ a firmware based distortion-correction curve in those radios. Icom's curve isn't real-time dynamic as in an Anan, rather it's a one-time correction curve burned in at the factory so it's not going to be as effective as the constantly adjusting correction employed by Thetis in an Anan. But it clearly does improve the IMD in the 7300 and 7610, at least per my own observations.

Mark
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Re: Competition for Pure Signal ?

Postby VK-JOE » Wed Oct 05, 2022 4:14 am

Here is my take on what ICOM is doing with their IC-PW2 as an alternative to ANAN pre-distortion - "Pure-Signal" ??

If you been waiting for an ANAN transceiver from Apache-Labs - you might be able to buy from ICOM a 7610 / PW2 combination - with DPD implementation.

ICOM to finally implement DPD in their IC-7610 SDR

icom_DPD.png
icom_DPD.png (128.24 KiB) Viewed 12801 times

Reading between the lines (no pun intended) - we can see that ICOM will most likely implement DPD function in the MachXO2 Family FPGA (https://www.latticesemi.com/-/media/LatticeSemi/Documents/DataSheets/MachXO23/FPGA-DS-02056-3-9-MachXO2-Family-Data-Sheet.ashx?document_id=38834) used in the 7610.

Looking at the schematics Icom IC-7610 Transceiver Service manual PDF View/Download (all-guidesbox.com) https://all-guidesbox.com/manual/1410608/icom-ic-7610-service-manual-107.html of the TX stages of the 7610 - there is certainly sufficient circuitry for the required RF sampling - to implement "stand-alone" DPD.

My guess is that Icom will most likely implement the DPD functionality on the 7610 , and despite the 7610 then being able to be a standalone 100W DPD enabled tranceiver - it will be linked (locked to be more pprecise) to the PW2 hardware in some way via interface cable & appropriate firmware to enable the DPD functionality (required for sampling) only when connected to the PW2 amplifier.

This will leverage the need to buy a PW2 to use DPD with a 7610 and visa versa - making more $$ for Icom.

Well at least there will be a 100% working system - with factory support and development from a Tier 1 manufacturer of Amateur Radio Equipment - ICOM - and most importantly have a transceiver with a DPD ;)

Having said ALL of the above - I still would like to get an ANAN radio (just so I can experiment with it)

@ w-u-2-o
Now if Icom would only get off their high horse and allow a transmit passband greater than 3KHz they'd own the ESSB market, too.

Could not agree more regarding this statement Scott :D
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w-u-2-o
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Re: Competition for Pure Signal ?

Postby w-u-2-o » Wed Oct 05, 2022 1:55 pm

Thanks for those block diagrams and schematics.

There is clearly an RF feedback path in the 7610 that could be used for predistortion linearization for the 7610 alone.

However, what remains a mystery is how they propose to linearize the PW2, as there is no obvious feedback path from the PW2 output back to the 7610.
Trucker
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Re: Competition for Pure Signal ?

Postby Trucker » Wed Oct 05, 2022 9:00 pm

I would think Icom would play it safe and if/when, they add predistortion, in the 7610 firmware, that they would allow it to work with or without the new amplifier. Otherwise, they could alienate current owners and future buyers. Not everyone who wants predistortion needs or wants an amplifier.
Just my thoughts.
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Re: Competition for Pure Signal ?

Postby VK-JOE » Thu Oct 06, 2022 3:16 pm

Trucker wrote: if/when, they add predistortion, in the 7610 firmware, that they would allow it to work with or without the new amplifier


Props to ICOM if they decided to do this - but I can almost guarantee - this will never happen - why?

Because Icom is a very marketing ($$) driven company.

The 7610 had been around for years - it’s not new - but it’s a dam good radio and even TODAY there is a high demand for this "old" radio which is quite unique.

(Just shows you how ahead of its time it was)

Icom has never (to my best knowledge) has done a major "functionality" update in their radios via firmware only. To date both the 7610 and the 7300 have had limited firmware enhancements.

A DPD enhancement - would be a major feature - worthy of a new model number for a stand alone radio - perhaps a 7620?

If Icom enables DPD on the 7610 standalone - it will be a "different radio" - so they can charge an incremental $ for the new features.

By locking the PDP functionality - to only work with the PW2 amp - they in effect are holding all the cards for much more $$

It’s aimed at SO2R market and that means operators who take this hobby seriously and have some big $$ to throw towards the appropriate station hardware.

It’s very clear from the Icom marketing to date, that they have chosen the 7610 to be "THE" radio for use with the PW2 and making the point that the DPD function will be via a 7610 firmware update to work with the PW2 only. This means if you want the PW2 to have DPD output - you MUST use the 7610 with it.

Hope you can see the logic behind this.

It is why they are unlikely to make the 7610 as a standalone DPD radio.

As a side, the output on the 7610 is squeaky clean - even without a dedicated DPD functionality - its already doing some good processing.

The real benefit of having the DPD on the 7610 (or any other radio driving an amplifier) is not to enhance the output of a already "clean" radio - but to make sure any external high power amplifier is as squeaky clean as the radio itself.

What better way to promote a "new" amplifier - the PW2, than introduce DPD to make sure its super-efficient and super clean!

The easiest way for Icom to do this is via the 7610 and locking this to thew PW2 for a great SO2R system.

Here is some speculation on how they are likely to do the "locking" of the 7610 to the PW2 ....

I think this will be done digitally.

The interface to the PW2 from the 7610 is via a multi pin control cable. This is most likely to be via one of the digital I/O sockets on the 7610.

Thinking conventional - we would expect some sort of RF sampling (-50db) from the PW2 to the 7610 - for the DPD system corrections which need to be created by the "exciter" - the 7610 in this instance. So how do they get the RF back to the 7610?

Perhaps they don't have a direct RF feedback.

They could sample the RF in the PW2 internal circuitry and quantize the output - this is relatively simple - because there is no processing - just quantizing and the digital "stream" can be fed back to the 7610 via the digital I/O for the 7610 to use in the firmware to realize full DPD functionality.

If this type of interface is adopted, Icom solves 2 problems - in effect rendering the 7610 useless on its own as a DPD system and at the same time "locks" the radio to work only with the PW2 as a DPD system.

All this is guesswork.

But if faced with the above task - get the DPD working with the 7610 locked to the PW2 - that's probably the best way to implement it!
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Re: Competition for Pure Signal ?

Postby VK-JOE » Tue Oct 25, 2022 1:49 am

Just want to share some information on possible availability date for the IC-PW2.

I have received some “unofficial” feedback from an Icom Sales employee that the official pricing for the IC-PW2 will be announced sometime in December 2022.

Once the price is announced – he said - the Icom Dealers will be able to place orders with Icom for the IC-PW2.

Icom’s “end of financial year” (Japan) is end of March 2023.

The expectation is that the IC-PW2 will start to ship BEFORE this date (EOFY) – most likely in the last week of March 2023.

Is the above information “reliable”?

Who knows?

– but it does make sense
– so, there is some plausibility.
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Re: Transmitter composite noise

Postby VK3ICM » Sat Jun 03, 2023 7:37 am

w-u-2-o wrote:Mark,

Nobody has a hardware architecture that will support it, with the possible exception of Flex and perhaps such niche products as SunSDR.



Hi Scott - I'm on an old IC-7610 Icom mailing list and recently I saw some chatter about the (maybe?) forthcoming PW-2 amp and it's marketed Industry First Digital Pre-Distortion (DPD) Function. Dubious, I read the marketing info as implying the amp itself would analyse the input and apply pre-distortion, but someone pointed out the schematics for the IC-7610 show hardware for pre-distortion feedback is in place so operation more like we are familiar with. If so, not sure what makes it an 'industry first.. 'digital?'

https://www.icomamerica.com/en/download ... ument=1137

Chris
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w9mdb
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Re: Transmitter composite noise

Postby w9mdb » Sat Jun 03, 2023 11:58 am

They qualified their statement -- "the world's first DPD as a linear amplifier for amateur radio".
Mike W9MDB
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Re: Competition for Pure Signal ?

Postby w-u-2-o » Sat Jun 03, 2023 1:49 pm

There's a link to the PW2 maintenance manual posted above. It's not entirely clear, but I've heard lately that the feedback path from the amp will come over the ALC connection to the 7610. I guess we'll see if they ever launch the PW2 for real instead of just talking about it. Even after they launch it when will the DPD firmware come? Who knows?

Meanwhile, it's worth mentioning that Elecraft has taken a more overt hardware approach with the clearly marked "TX SMPL IN" connector on the back of the K4. Their KPA1500 already has an internal coupler. Perhaps they'll add a 500W coupler to their product line to support the KPA500. BUT...Elecraft continues to be in bugfix/basic feature mode where K4 firmware is concerned. So again it's "Who knows?" when linearization will come to the K4.
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Re: Transmitter composite noise

Postby K1LSB » Sat Jun 03, 2023 3:04 pm

w9mdb wrote:They qualified their statement -- "the world's first DPD as a linear amplifier for amateur radio".

And even that is not entirely the correct claim.

Specifically, the claim is "This technology corrects the signal distortion from the IC-PW2, by applying inverse distortion to the output signal from the IC-7610 exciter in advance". (emphasis added)

That statement does not claim that the IC-PW2 is able to correct for any signal distortion originating in the IC-7610 exciter. The IC-PW2 is only aware of the output signal coming from the IC-7610, not the input signal going into the IC-7610. So the IC-PW2 can only correct for distortion generated internally in the IC-PW2. It does not, and cannot, correct for any distortion generated in the exciter.

Mark
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Re: Competition for Pure Signal ?

Postby JJ4SDR » Wed Sep 13, 2023 3:25 pm

K9UR posted this (after my signature) on the B26-PA (Solid State amp from Germany, also known as RF-KIT) Groups page yesterday. I will believe when I see it. And, of course one can use an external RF coupler on an amp.

Can anyone confirm what is written below?

Juha
NI2M

"As long as the amp has a pre distortion tap, the icom 7610 (once new firmware is released) should allow for it on any amp that provides that tap. We will know details when the feature is released but likely Icom 7610 joins Anan and Hermes in the predistortion feature set (with any amp). "
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Trucker
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Re: Competition for Pure Signal ?

Postby Trucker » Wed Sep 13, 2023 4:15 pm

New firmware coming for the Icom 7610 for Digital Pre-Destortion. ( Icom's term)
It will work standalone and with the soon to be released, PW-2 amplifier. Supposedly before the end of this year. And it should work with other amplifiers with the proper connections.
James
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https://www.icomjapan.com/lineup/products/IC-7610/
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Re: Competition for Pure Signal ?

Postby K1LSB » Wed Sep 13, 2023 6:54 pm

It's high time someone besides Apache Labs offered that feature. Rob Sherwood himself has made multiple comments over the past couple of years that none of the Big Three have appeared to show much interest in cleaning up their TX act, they're seemingly all obsessed with RX bragging rights.

Speaking for myself, I'll never buy another transceiver that doesn't offer adaptive predistortion. Indeed, that's the Number One reason I bought an Anan (there are several other strong reasons I chose the ANAN, such as true phase-coherent Diversity Receive and crazy-wide TX passband width).

But kudos to ICOM for finally stepping up to the plate!

Mark
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Re: Competition for Pure Signal ?

Postby w-u-2-o » Wed Sep 13, 2023 8:02 pm

Let it be clearly stated: it's not Apache Labs who offers PureSignal, it's the volunteer, open source developers who produced the WDSP library, the Thetis SDR client software that depends on WDSP, and also PowerSDR mRX PS before Thetis. In particular, Dr. Warren Pratt, NR0V.

Any hardware that provides a compatible interface to Thetis using either openHPSDR communications Protocol 1 or Protocol 2 will run PureSignal. That includes Apache Labs, Red Pitaya, Hermes Lite, and TRX Duo, at a minimum (there may be others).

Some versions of this hardware, including older Apache designs, require an additional switch and coupler be added, but that is a small modification.

It's going to be interesting to see how well the Icom scheme works, or if it is going to remain vaporware. The very tenuous rumors I've heard is that the 7610 is going to use the ALC input as the feedback port, but we'll see.

Elecraft specifically designed an input and internal hardware into the K4 for linearization, but I've not seen any chatter on when or if they will release firmware with that capability.
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Re: Competition for Pure Signal ?

Postby Trucker » Fri Nov 24, 2023 11:25 pm

Just a quick update. Icom has released their version of Adaptive Pre-Destortion that they call Digital Pre-Destortion on their website in Japan. Icom USA doesn't show it yet. But, that hasn't stopped several Icom 7610 users from downloading it and installing it. So far, from their posts on groups.io for the 7610, it appears to work. But requires several setup steps to get going.
I have a 7610 in my shack. But, I think I will wait until the official US version shows up on Icom USA website before trying it on my 7610.
I had a developer from Flex Radio tell me several months ago that they have had APD running on their test bench. But, he didn't have any idea if,or when, Flex Radio may offer it. ( my bet if they do, it will be in a paid upgrade)
I like how well APD works with my 8000DLE and Thetis .
James
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Re: Competition for Pure Signal ?

Postby K9RX » Sat Nov 25, 2023 1:16 pm

I read the 7610 info on their group - this sounds promising. I see this as a win for ham radio. Considering the actual number of Anan users is tiny compared to the installed base of 7610's ... this can only help towards cleaning up the bands. With Elecraft working on it - Flex supposedly having it in test... we might be able to 'snuggle up' to others on the band and not know they're there, or them that we're there. Kudos to all the developers working on this - FINALLY.

Gary
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w-u-2-o
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Re: Competition for Pure Signal ?

Postby w-u-2-o » Sat Nov 25, 2023 6:44 pm

Thanks for the "heads up" on this. I also read through all of the discussion on the 7610 groups.io group, and looked at both Rob S's and Adam F's results. Icom predistortion is quite credible! Somewhere between 20 and 30dB of improvement similar to PureSignal. Icom is to be congratulated!

The one mystery they have not unraveled yet is what kind of signals are coming out of the IC-PW2 amp into the 7610 ALC port during predistortion operation. Once that is figured out perhaps it may be possible to use Icom predistortion with any external amp.

Elecraft seems a lot closer than Flex. They better get a move on :D
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Re: Competition for Pure Signal ?

Postby K1LSB » Sat Nov 25, 2023 7:09 pm

Per Paul's (W9AC) post in that group, "With DPD engaged, the target ALC voltage at the ALC jack is replaced with a target sampled power or RF voltage level...Among other FAQ issues, what must be confirmed is the minimum and maximum level at the IC-7610 ALC jack with DPD activated."

Not sure where he's getting his info but it sounds reasonable to me.

Here's his post:

https://groups.io/g/ic-7610/message/31644

Mark

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