Help cleaning up an LSB transmission

[dragon48]

Earlier tonight, I picked up what was clearly a 2 way conversation on 7175 KHZ LSB. The signal was weak, but even if it were strong, I wouldn't have been able to decipher the voices. It sounded like one speaker had inhaled helium and the other was R2-D2, but somebody had modified the speed of his voice.

Is there some way to fine-tune LSB broadcasts on my AOR 8200 MK11 so I can pick these up better in the future? Also, is there PC software that can work with sound clips of these transmissions, to "normalize" the audio?

Here is a clip of what I picked up. I'm wondering if one of the experienced Dxers (is that a verb?) could decipher this.

https://soundcloud.com/user-437184959/distorted

 

[ridgescan]

Me again not trollin ya! You weren't tuned exactly on the frequency they were on-you were too high.
Your LSB two-way convo in the 40 meter HAM band was likely taking place point 5kHz down from 7175 on 7174.5, so you need to change your tuning steps to .1kHz from 1kHz to fine tune it in.
They likely moved off a half notch to get away from some bleedover from other guys close by.
Not sure if your AOR has .1kHz steps or not-it should.

 

[dragon48]

Thanks again for the advice. It does have .1 KHZ steps. From something I just looked up: (AR8200 - The RadioReference Wiki) Auto, 50, 100, 200, 500Hz; 1, 2, 5, 6.25, 8.33, 9, 10, 12.5, 20, 25, 30, 50, 100kHz steps (also selectable in 50Hz steps-to 999.95kHz) I don't remember how I was stepping then, but the signal was so weak, that it is possible that I may have missed a clearer signal.

While I have you here, can you answer a different question that I was going to post on a different thread:

I was playing around manually scanning in A.M. mode, and got a strong, but unintelligible signal at 7280 KHZ. When I switched modes to WFM, I heard a clear, almost full signal. It was a Spanish language broadcast. I didn't stick around long enough to identify it and couldn't make out any accents, but I did hear the speaker reference Havana a few times, so perhaps it was Cuban. I then was able to get the same station in AM mode at 7360 KHZ, also strong and clear.

To be clear, in WFM mode, I was able to get the signal a number of clicks (I don't remember my stepping) up or down from 7280.

How does the science of this work? Why did I get the same station on WFM 80 KHZ lower than the (I assume) intended AM broadcast?

I need to get to sleep as it is 12:05 A.M. in NY, and will check out you (hopeful reply in the morning. This is a ton of fun—I'll try and help others one day when I become good at this.

Thanks

 

[NDRADIONUT]

Look up slope detection...

 

[ridgescan]

I'm afraid you caught me at a loss on this one. Not sure if the receiver is single conversion in HF or more-but it sounds to me via your explanation of occurrence that it might be intermod from a strong nearby AM Spanish broadcaster. The described frequencies 7280 and 7360 don't jive with any Spanish SW BCs that I know of.

 

[dragon48]

I picked up the transmission earlier tonight for around 10 minutes, before the signal completely cut out, and I was unable to get it back. You can hear the near abrupt loss of signal at the end of the third sound clip.

I think I may have solved the mystery. I may have mis-typed 7360 in my post yesterday, but the picture that I took of my scanner shows 7365, and according to Short-Wave Frequency Schedule for 7365 kHz at 03:59GMT, I was listening to Radio Marti, the U.S. Spanish Language broadcast, aimed at Cuba, broadcasting (this schedule) from Greenville South Carolina.


The first clip is from last night. The next 2 (in order) are from earlier tonight.

https://soundcloud.com/user-437184959/7365-khz

https://soundcloud.com/user-437184959/7365-khz-2

https://soundcloud.com/user-437184959/7365-khz-3

I'm listening to a live feed now, (Radio Martí - Miami, FL - Listen Online) and the speakers are different than those I heard and recorded, but it has been more than 2 hours since I was able to get a signal anywhere near 7365. I'll try tomorrow night to listen to the internet stream while I pick up the frequency on the radio, to see if they sync up,

Can any native Spanish speakers determine form the clips whether this is indeed radio marti, as I don't remember hearing any station identifiers.

 

[paulears]

Don't forget that the two people having the conversation were NOT on the same frequency. They use RIT, receiver incremental tuning - to shift the received audio to the correct pitch, by offsetting the RX and TX frequencies - both these users will hear each other perfectly - as a listener, you have two different frequencies to tune each time they swap over. Some receivers have a switchable shift, others don't - so if you have the capability, you tune one in without the shift, then engage the shift and tune the other with it. Pressing the shift button each over sorts the problem. They're just on different frequencies and it's quite normal. Modern radios don't really object.

 

[cmdrwill]

The 'Clarafier' knob.....

 

[N8IAA]

The 'Clarafier' knob.....

No 'clarifier' on a HT.
Larry

 

[dragon48]

No 'clarifier' on a HT.
Larry

Thanks to Ridgescan, I figured the issue out, as I ran into another LSB broadcast. I just need to scan while stepping with the smallest increment and eventually the voices clarify. I don't remember the directions, (up or down) but the pitch and speed were higher as I scanned one way and the pitch and speed went lower in the other direction. Eventually, I found the intelligible voices.

 

[paulears]

The speed doesn't change, only the pitch. remember that with Single Side Band, the transmitter doesn't waste energy with the carrier wave and removes one of the two sidebands. Your receiver puts the missing bits back in, and then demodulates it. Get the frequency slightly wrong, and the chipmunks is the result.

 

[k9rzz]

Since no one has specifically mentioned this yet, I will.

You have to ZERO BEAT the station you want to listen to, so you still have to match their frequency exactly. So, the frequency that shows on your radio, must match the center line here in this diagram. If you're off, he will sound funny. See if this helps: