Messages

76

General Radio Discussion / Re: Q: "Anyone seen the stepladder?"

« on: March 10, 2020, 0336 UTC »

I guess this is what they found when investigating common point shifts eh?  Must have been fun to watch when it rains.

More silliness...and a repost https://youtu.be/lMuJKsUjD_o

+-RH

77

The RF Workbench / Re: Icom 718 problems

« on: March 09, 2020, 1653 UTC »

Sounds like either a lightning hit, or the transmit/receive switching failed to operate correctly.

+-RH

78

Equipment / Re: Spitfire Am transmitter

« on: March 09, 2020, 0143 UTC »

FWIW, I have had very little contact with the newer boxes, and most of what I've heard is second hand or from sales reps.  The point being is that few folks are monitoring off air these days and latency is less of a priority.  Add to that in the typical airchain the processor is only one source of latency.  Often the STL path is far from instantaneous, and most of the newer AOIP routing systems have some delay as well.  30-50mS seems the be the break point where it becomes hard to use in a live situation, and by the time you approach 100mS I can't use off air monitoring.  The effect is weird, you start to stutter!

Running HD?  8 seconds minimum coding and buffering delay for most HD systems.  I believe DRM has similar delay, perhaps less.

Anyway, sorry to derail the topic.  Perhaps we could pick this up somewhere else.

+-RH

79

General Radio Discussion / Re: What is replacing Short Wave radio?

« on: March 08, 2020, 2035 UTC »

IDK, give me wideband AM back on the Kiwis anyday.  If RCI had been running conventional AM, at least I could have heard them.  With DRM all I got was the occasional blip of audio.

+-RH

80

Equipment / Re: Spitfire Am transmitter

« on: March 08, 2020, 2018 UTC »

I was told that with ASIO drivers under windows it can be reduced to 20mS.  That said, bass distortion cancellation is reduced.  Long waveforms take time to process.  Even the delay in a modern optimod or omnia is on the order of a second or two.  The industry has given up on low latency processing for all things but talent processing, mainly because no one monitors off air anymore.  Thanks HD Radio...

+-RH

81

Equipment / Re: Spitfire Am transmitter

« on: March 07, 2020, 2031 UTC »

The end plan is to replace the current intel based machine running ST with the pi.  It would be neat to have a pop-out touch screen for changing parameters and such.  Latency is about 1/4 second, which isn't bad considering the  small amount of onboard processing power.  I've tried lowering it to 100mS or so and it wasn't real happy.  Good thermal management is a must, and even with the fancy case, CPU temp runs about 25 degrees C over ambient.  That is not much of a problem now, but might be when its outside in a rack and the ambient is pushing 40C.

+-RH

82

General Radio Discussion / Re: Applaud/Smite Karma Ratings?

« on: March 07, 2020, 0600 UTC »

Admins might.  Us peasants, nope.

+-RH

83

General Radio Discussion / Re: Applaud/Smite Karma Ratings?

« on: March 06, 2020, 2231 UTC »

Clearly the sardines...

+-RH

84

Huh? / Re: Oregon Engineer Makes History With New Traffic Light Timing Formula

« on: March 06, 2020, 2022 UTC »

The vote vindicates the theory of Mats Järlström, who was fined $500 by the Oregon State Board of Examiners for Engineering and Land Surveying for publicly criticizing traffic light timing without first obtaining a professional engineering license.

https://ij.org/press-release/oregon-engineer-makes-history-with-new-traffic-light-timing-formula/

Fined $500 for public criticism?  So much for freedom of speech.

...And they tried to force a gag order on him to boot.  Nice state government they got there.

+-RH

85

General Radio Discussion / Applaud/Smite Karma Ratings?

« on: March 05, 2020, 1913 UTC »

I see we have a new board feature.  Perhaps this shall foster better civility?

+-RH

86

General Radio Discussion / Re: Oakland A's leave radio in Bay Area, what would Charlie Finley think?

« on: February 25, 2020, 1303 UTC »

I know KHTK is a 50k Class B station, I don't know how low they transmit at night.

License says 50KW day and night, directional to the NNW/SSE from a 5 tower array near Galt, CA.  Coverage should extend to Oakland.

+-RH

87

Equipment / Re: Spitfire Am transmitter

« on: February 24, 2020, 0503 UTC »

I got stereotool to run on a pi4 and a hifiberry card last weekend.  Uses 1/3 the dc of my current processor, sounds good too 😊

+-RH

88

Equipment / Re: Spitfire Am transmitter

« on: February 22, 2020, 1408 UTC »

That's why it sucks.  You need to build a tuned antenna for something that short.  Something like this...



To add insult to injury, anything in you house that radiates will get into the powerline, and cause apparent hum in your signal.  Its actually RF getting into all the rectifiers in every switching supply in the house and through nonlinear mixing, superimposing 120Hz on the signal and re-radiating it.  The transmit antenna should really be outside if you want to be able to listen to it.

+-RH

89

Equipment / Re: Spitfire Am transmitter

« on: February 22, 2020, 0328 UTC »

Does the provided antenna have a loading coil or is it just a wire with a connector on the end?

+-RH

90

The RF Workbench / Re: Cheap and easy PWM modulator for small AM transmitters

« on: February 21, 2020, 2215 UTC »

That's my understanding.  The pot adjusts the cutoff frequency in LPF mode.  Tritone should really be called fullrange (20-20,000).

+-RH