Flex-6700 & Diversity
In my earlier, somewhat tongue-in-cheek post on diversity with the Flex-6700, I probably sounded like I had discovered the New World! The New World in this case wasn't the concept (with which I'm very familiar) but rather the real world first-hand experience of hearing it in action.
Since my first in-anger use of Diversity was in the ARRL Sweepstakes Phone weekend, I didn't have the time or the thoughtfulness to make any recordings. This past weekend provided an opportunity to remedy this and capture some recordings during the ARRL 160m contest. Rather than an all out BIC (Butt-in-chair) effort, my focus this year was US state hunting to get closer to 160m WAS. This provided plently of time in-between fishing for wanted states to make recordings.
Station setup and recordings
I set up my Flex-6700 for diversity reception using the TX antenna (55' top loaded vertical) for slice A (left channel) and a PixelLoop for slice B (right channel). The TX antenna has a good radial field and is separated from the PixelLoop by roughly 500'.
With the exception of the first recording, the balance of the two channels was full left and full right for slice A and B respectively. The first recording used the same setting I'd used during ARRL Sweepstakes with slice A set with the pan control centered and slice B full right. The first recording also has poorly matched audio levels between the two channels. I tried with subsequent recordings to equalize the audio levels between the two channels and also adjust AGC-T to match the relative noise levels between the two antennas. I'll leave you to judge but listening to all three recordings several times, I can't tell much difference.
The recordings were all made using the Mac OS X version of Audacity and exported in MP3 format. No post processing was done on any of the recordings - they are all uneditted. I had to resort to a plug-in USB sound device to get stereo recordings as the native Mac microphone inout is mono-only.
Listening to the recordings
You MUST use a stereo headset, ear buds or headphones to get the full diversity experience. This is the only way to insure that you hear the audio without multi-path or echo effects resulting from speaker placement and room effects.
You might want to download the audio files and use Audacity as the audio player so that you get to see the audio waveforms as you listen. This helps you see what you are hearing and visualize what you wouldn't have heard without diversity.
To listen, click on the links below or right click and select "Save As..." to download the file to your own computer/device.
Recording #1: KO7X in Wyoming (length 6:43, download size 6.4MB)
Comments: A longer recording which captures several mini pile-ups showing how the diversity helps "spread" the stations out around your head. Many places where there were deep fades on the vertical that didn't occur on the loop.
Recording #2: N8II in West Virgina (length 2:36, download size 2.5 MB)
Comments: WV was one of the states I needed for WAS. This recording includes me working him! Again some good examples of where one or other of the antennas would fade but copy wasn't serevely impacted.
Recording #3: WF2W in New York (length 3:07, download size 3 MB)
Comments: Good examples of diversity rescued fades but mostly WF2W calling CQ - he was lonely so eventually I called him! Astute observers of the sound clip in Audactiy will notice that there is a roughly 7 mS time delta with the right channel leading the left by that amount. I had enabled APF for this recording but only enabled it on slice A! Currently the DSP functions in diversity mode do not track one another - if you enable APF in one, you need to enable it in the other!
I continue to be very impressed with diversity on the Flex-6700 - so much so that I'm thinking this should be standard operating procedure at K6TU for bands where separate antennas are available. The PixelLoop works great from VLF to 10m so I've got that covered! In a word - Awesome!
There are certainly other radios available that support diversity. For me, the combination of reduced operator fatigue, excellent AGC characteristics and how signals just pop out of the noise makes the Flex-6700 my tool of choice for Dxing and Contesting.
If you aren't using a Flex 6000 6700 radio, you aren't using the best tool for the job.