Adding dB Gain to your Transmit Signal. Howe much difference?
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- Опубликовано: 12 сен 2024
- There are a number of ways to add dB gain to your transmitted signal. But how much difference does 3dB or 6dB make? Is it worth the effort! Peter G3OJV demonstrates using calibrated audio tracks.
In this video I deliberately started with a difficult to hear signal that represented 0dB gain and might be ne a typical 100W signal in competition with heavy noise.
I started listening to this on speakers in a room with an air conditioner running. Then I switched to a pair of Bose QC-25 noise reduction headphones. About the same improvement as a 6 dB increase in the transmit power. Even if you don't have noise reduction headphones, you should always use headphones when trying to work weaker stations.
This is a very good video. Thank you very much. In town I fight EF interference so the idea of getting my horizontal di pole even higher is a great one. I use a telescoping wire in the middle and then the other ends come down to about 8 feet but if I added to more telescoping poles the whole thing will be 30 feet in the air! Thanks for your knowledge.
That was a very good demonstration, Peter. I like how you mentioned that the antenna can provide gain on Tx and Rcv.
Has I cut my teeth on QRP and I only have 100W equipment I've learned to let my ears and S-Meter judge whether I should attempt to work a station and I work the vast majority of stations I call with only 20W. Of course I seldom call stations that I am not receiving as an S-9, which implies that they probably will hear my station as an S-6 or better. I say better because as a portable station I usually have a modest gain wire antenna, but often the strong stations have higher gain beam antennas that amplify my signal so I often get accurate 58 and 59 reports.
In a pinch for a rare station I can turn up to 80W for one more S-Unit or 6dBr, which is worthwhile.
Even the 1dBr compression gain was noticeable in your demo. Great job!
Interesting, good demo and the compression certainly helped a lot.
Peter thank you for this novel approach to explaining this subject. You demonstrated this very well.
Good basic principles to know.
Another good video Peter. Another way to find out about ones own signal would be to monitor it using a websdr. That can help with trying out different power levels and is also a good tool for setting audio quality, Dave G8XDD
Very good demonstration Peter! The best from LB1NH in Oslo Norway! 🙂
Mount a yogurt or cottage cheese cup (with a little foam around the inside) backwards on your mic, adds about 6dB to the midrange audio when your mouth is the right distance from the mic.
Very clever 👌. Always wondered what the difference sounds like at the margins and now I know 👏
I always try and wring every bit out of the antenna , good co-ax , good connections , and try to eliminate common mode to an absolute minimum . I had a QSO with Fred G0AOJ , and he kindly helped me set the right level of compression , and mike gain . so don't be afraid to ask other hams about the quality of your audio .
Thank you. Excellent video
Excellent and informative demo, Peter.. Thank you..
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Glad you enjoyed it
Well presented as always. Of course compression does have the advantage of being "free". Sometimes we can make substantial improvements to an antenna system efficiency without having any gain as such. I remember years ago with aa 160m inverted L fed against ground adding about 100m of radials and the jump in efficiency was such that a friend could not believe that I was stronger using my FT817 than I had previously been with a 200w radio. A bit of an unusual scenario but a big improvement for very little time, effort or money. I bet I could have gained 6dB with just a bucket of water 🙂 Thank you for another thought provoking video.
Many thanks for sharing. 73 Peter
Very informative video. You got the result that I expected but it was nice to actually hear the difference with compression at the three different levels. I'm curious as to the amount of compression you used on the 705.
Thanks for great vid!
I don't think anything here will contradict what you said: On transmit, compression adds radiated power (through processing gain) because you drew more energy to fill in the more quiet bits. Directional antennas make any input power appear louder in the direction of the main lobe (spatial gain, the radiated power goes up on *that* main axis, though the *total* radiated power is not increased, it's just been redistributed in space). On receive, even if the directional antenna did not increase the signal power to your input, the real advantage I see is the signal to noise gain due to the spatial filtering from that directionality, which when summed over all angles off the main response lobe reduces the total input power to your receiver from isotropic rf noise (assumed, but easiest and it's what directional gain against noise assumes) from all directions other than the one your pointed at.
Informative as always.
Great job thanks
Great video Peter, thank you so much. I used to struggle with noise, not ant more since I got the xiegu noise reduction unit, the nr1. I tried a 2 ele parasitic vertical to increase gain in tx and rx, also the best amplifier I found was being by the sea, 2 -4 s points at the other end, it was great.
Thanks Peter for your knowledge 73 zl3xdj
Very interesting video Peter. Thanks for this great demonstration.
73 de Kevin, VK4KK
Many thanks!
Very interesting and good information, thanks and great videos
Glad you enjoyed it
👍👍👍
Don't you add POWER to your TX and DB to your RX???
dB is a measure of either gain or power changes. So if you change Tx poser you effect a dB change.
Hello from ms
Hello
You must increase audio by 6 dB to double the audio power level. Ron W4BIN
You are confusing power change with perceived audio level. They are different.
Useful, thanks Peter
73 Rob g3rce