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Author Topic: Flex-5000A CW Impressions  (Read 32491 times)
WD4ELG
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Posts: 873




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« Reply #90 on: January 11, 2013, 06:58:06 AM »

Thanks, Stan.  Now you have me thinking...
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K9IUQ
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Posts: 1763




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« Reply #91 on: January 11, 2013, 08:49:20 AM »

Thanks, Stan.  Now you have me thinking...

This is good. Doing your own testing and not relying on others opinions (especially peer pressure opinions like is seen on the Flex Reflectors) is the way I do things.

I step on many toes and have lost friends because I am truthful and honest. It is the price I pay for thinking for myself......  Wink

Stan K9IUQ
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KA4KOE
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Posts: 206


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« Reply #92 on: January 14, 2013, 12:46:02 PM »

Missing dits? I wondered why my morse with a paddle had issues. The bug can fix that!
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EI3GD
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Posts: 3




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« Reply #93 on: April 04, 2013, 03:52:31 PM »

Folks,
Has the new release (2.5.3) made any improvements to the reported CW delay or 'stutter'?

I use a Flex 3000 and found a noticeable delay when using VAC, but listening to CW direct from the front panel (headphone socket) seems to have no delay. Does this work on the 5000?

Thanks
Ray
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K0OD
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Posts: 2557




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« Reply #94 on: April 04, 2013, 04:44:01 PM »

I've never had any such CW delay on my Flex-5000. Owned it for 3+ years.

I use it (with my own keyer, BTW) all the time on CW at speeds between 20-35 wpm. My radio has had a persistent problem that I've referred to as a slight squelch tail sound that I hear and can see on the Flex scope sometime when the radio switches from transmit to receive. Varies with the band and other things. Fairly minor.

2.5.3 didn't affect keying when I installed it several months ago. As I recall, that version didn't deal with keying according to the release notes. Flex is working on another update to PSDR that should be released soon.
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W6RMK
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Posts: 651




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« Reply #95 on: April 05, 2013, 06:34:40 PM »

Anyone know what architecture Flex uses when sending CW? I bet the key input gets sent up the Firewire port to the PC to be processed before being sent back down the link to the radio hardware as an RF waveform
Midi messages
Quote

They would have been better off putting a $0.50 Pic MCU in the box and using that to directly key the transmitter, even if the radio's internal firmware has to generate the RF waveform directly. A simple on-off keyed CW signal can't be that hard to generate to require a fast PC's processing power.

That's not how it generates CW (nor how any SDR would generate it): you're thinking in terms of traditional analog radios where you do something like turn the final amplifier on and off (or perhaps one of the stages, and then feed it to a linear amp).

In an SDR, you just generate the sine wave (envelope shaped to reduce key clicks) that you want transmitted.  Think in terms of something like hooking the output of a code practice oscillator to the input of a SSB rig.

The challenge with the PowerSDR software architecture is that the latency through the chain can vary somewhat.  The transmitted signal is ok, but has a variable delay from the input to the chain, so if you listen to your own transmitted signal, you'll be confused.  The recipient on the other end of the path doesn't care.. he or she hears normal CW.  Another term for this is "pipeline delay" and such a delay exists in ALL radios (even analog ones).  The delay through a filter with a given bandwidth is roughly 1/Bandwidth * number of sections. So if you have a 50 Hz wide filter, you're going to have a 20 ms delay (at least).  In the Power SDR, the delay is more about the block size in the DSP. SHort blocks mean shorter absolute delay, but the filter performance isn't as good.  You want a 1 Hz transition in a brick wall filter? that's a 1 second delay.

The other challenge faced by the PowerSDR architecture is T/R switching.  In the early versions (fixed at least 4-5 years ago, I think), you had to wait for the audio buffer to finish before it could be "turned around" to the other direction. That's probably the "missing dit" thing.  When they fixed the buffering so that it ran full duplex (at a cost of doubling the CPU burden), that particular problem went away..

The other tricky aspect to the PowerSDR architecture is that it potentially has multiple blocks of data stacked up through the chain in both directions.  You really, really don't want to have the Transmit DACs "run dry" (because you'll be emitting a big CW carrier at the DDS center frequency with fixed values of I and Q until the next set of samples arrives), so you want to have a few blocks queued up, in case the PC decides to go do something else for a short time.  If you're watching a DVD and you hesitate a frame or two, you might not notice.  But if the last set of samples happened to be full scale I & Q on a Flex, then you're transmitting full power carrier until the next samples arrive.  A good design (which they may have done in the firmware between 1394/Firewire and DACs) would have some default "zero" value (chosen to minimize feedthrough of the DDS) to clock out if samples don't arrive over the firewire in time. 

In any case, the need to have extra blocks in the pipeline so the FIFO doesn't run dry also leads to longer delays.
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W6UV
Member

Posts: 538




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« Reply #96 on: April 15, 2013, 02:51:29 PM »

Anyone know what architecture Flex uses when sending CW? I bet the key input gets sent up the Firewire port to the PC to be processed before being sent back down the link to the radio hardware as an RF waveform
Midi messages
Quote

They would have been better off putting a $0.50 Pic MCU in the box and using that to directly key the transmitter, even if the radio's internal firmware has to generate the RF waveform directly. A simple on-off keyed CW signal can't be that hard to generate to require a fast PC's processing power.

That's not how it generates CW (nor how any SDR would generate it): you're thinking in terms of traditional analog radios where you do something like turn the final amplifier on and off (or perhaps one of the stages, and then feed it to a linear amp).

In an SDR, you just generate the sine wave (envelope shaped to reduce key clicks) that you want transmitted.  Think in terms of something like hooking the output of a code practice oscillator to the input of a SSB rig.

Thanks for the explanation. That approach sounds convoluted and bound to cause problems (like the lag I saw).

I was never able to come to grips with CW on the Flex and that's one of the reasons why I sold it. I now have a Yaesu FTdx-5000 and it's bullet-proof on CW. I'm happy.
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EI3GD
Member

Posts: 3




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« Reply #97 on: April 19, 2013, 02:34:31 PM »

Just been testing the newly released PSDR version 2.6.4 on my 3k and it seems 100% on cw to me. No extra or missing elements.
I really can't see any problems, it's rock solid. And when using the front head phone socket there is zero delay, at none that I could detect at 28 wpm sending.

73
Ray
Ei3gd
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AF4RK
Member

Posts: 39




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« Reply #98 on: May 12, 2013, 02:15:49 PM »

I have a Flex radio 1500. I built a 555 side tone oscillator that also keys the Flex radio. I operate in CW contests with N1MM and WinKeyer with no problems. I feed the side tone into an audio mixer so that I hear it in my ear buds along with the radio. True, the internal sidetone/keyer is useless. Try disconnecting the antenna and listen to the delay. You're not hearing what is on the air, which is an occasional problem with the "hotshot" CW contest guys. I miss a letter sometimes on receive. But I had 367 Q's in the ARRL CW SS with the Flex. by the way, anyone who owns a Flex radio, and I really like mine, should ignore any of their tech support. It took me a year to finally buy a decent computer, at which time the intermittent noise and red x on the display disappeared. All of the complicated suggestions were very misleading if well intentioned. With the I3 and ASUSTeK  P8H61-M motherboard , the operation of the Flex is flawless. I use Mini Deluxe and DM780 for casual digital and N1MM / FLDIGI for serious RTTY contesting using the Flex connector Line In / Out instead of VAC. VAC, another source of delay, about 1 second, which is critical for RTTY contesting.  I am very pleased with my Flex and would not go back to "normal" radios.
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W6UV
Member

Posts: 538




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« Reply #99 on: May 14, 2013, 11:00:45 AM »

I have a Flex radio 1500. I built a 555 side tone oscillator that also keys the Flex radio. I operate in CW contests with N1MM and WinKeyer with no problems. I feed the side tone into an audio mixer so that I hear it in my ear buds along with the radio. True, the internal sidetone/keyer is useless. Try disconnecting the antenna and listen to the delay. You're not hearing what is on the air, which is an occasional problem with the "hotshot" CW contest guys. I miss a letter sometimes on receive. But I had 367 Q's in the ARRL CW SS with the Flex. by the way, anyone who owns a Flex radio, and I really like mine, should ignore any of their tech support. It took me a year to finally buy a decent computer, at which time the intermittent noise and red x on the display disappeared. All of the complicated suggestions were very misleading if well intentioned. With the I3 and ASUSTeK  P8H61-M motherboard , the operation of the Flex is flawless. I use Mini Deluxe and DM780 for casual digital and N1MM / FLDIGI for serious RTTY contesting using the Flex connector Line In / Out instead of VAC. VAC, another source of delay, about 1 second, which is critical for RTTY contesting.  I am very pleased with my Flex and would not go back to "normal" radios.

Looks like you have work-arounds for most of the lag issues. CW was the only one that bothered me, and I never found a satisfactory solution that worked for me.
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