Have a stop at the light and narrow the sweep to 1MHz at a point in the peak area and see it there are spikes related to 60/120 Hz . Adjustment of the sweep rate will determine the interval of the spikes of the wide band noise.
Switching supplies have a more stable appearance in spectrum noise but the individual spikes will drift a little with temperature.
Since it is commercial operation, the interference will likely meet class A limits. The limits suck in my opinion.
I pulled the gear out of my truck when the weather got bad. I was seeing around -82 at 5 meters from the traffic light. Seems like the green led's are the worst. Will be a project for winter to determine who mfg the LED assemblies.
Good question is how they manage to put class A limits on outdoor devices!, especially traffic signals and streetlights that are now in unshielded fiberglass or ABS plastic enclosures.
As you know, all this noise is AM/SSB and it's additive
What is the level of the interference? Does it exceed levels for class A devices. Or class B for consumer use (just for interest sake). Devices that meet those levels can still be received and cause interference.
Switching power supplies are usually the source.
What is the scope? I live by the IFR1200S for tracking radio noise because of its excellent analog performance and adjustable sweep rate.
Actual "lamps" are LED arrays, not incandescent bulbs. Stainless enclosures made by Hennessy Products in Chambersburg PA. All wirung is underground or inside the steel poles and crossarms. There is no radio telemetry interconnecting intersections. Some intersections have siren detectors with blue pendant lights.
Have a stop at the light and narrow the sweep to 1MHz at a point in the peak area and see it there are spikes related to 60/120 Hz . Adjustment of the sweep rate will determine the interval of the spikes of the wide band noise.
Switching supplies have a more stable appearance in spectrum noise but the individual spikes will drift a little with temperature.
Since it is commercial operation, the interference will likely meet class A limits. The limits suck in my opinion.
halohms 1 year ago
@halohms
I pulled the gear out of my truck when the weather got bad. I was seeing around -82 at 5 meters from the traffic light. Seems like the green led's are the worst. Will be a project for winter to determine who mfg the LED assemblies.
Good question is how they manage to put class A limits on outdoor devices!, especially traffic signals and streetlights that are now in unshielded fiberglass or ABS plastic enclosures.
As you know, all this noise is AM/SSB and it's additive
ClevTV 1 year ago
What is the level of the interference? Does it exceed levels for class A devices. Or class B for consumer use (just for interest sake). Devices that meet those levels can still be received and cause interference.
Switching power supplies are usually the source.
What is the scope? I live by the IFR1200S for tracking radio noise because of its excellent analog performance and adjustable sweep rate.
halohms 1 year ago
@halohms
bottom of the sweep is -100, the sweeping blip when I'm stopped is between -85 and 180 dBm.
Spectrum analyzer is an HP 8558.
I do not have an isotropic antenna and can't get it within a meter of the light easily.
I do have a 110-550 broadband capacity hat comming in.
ClevTV 1 year ago
Actual "lamps" are LED arrays, not incandescent bulbs. Stainless enclosures made by Hennessy Products in Chambersburg PA. All wirung is underground or inside the steel poles and crossarms. There is no radio telemetry interconnecting intersections. Some intersections have siren detectors with blue pendant lights.
ClevTV 1 year ago