Questions tagged [rfi]

Use this tag for questions regarding RFI (Radio Frequency Interference).

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5
votes
2answers
130 views

Will a HF beam antenna on rooftop building interfere with other antennas there

I am moving into an apartment on the top floor of a building and I intend to install a HF beam antenna for 20 to 10 meters, on the rooftop of the building. I notice that there are already some ...
2
votes
1answer
62 views

What would cause this RF noise pattern? (Hum with associated "flapping" and beeping)

In quite a lot of places below 7000kHz I see a repeated noise figure. A hum, then about 12kHz above it a "flapping" with beeping noise, and then about 50kHz from that whistling with three ...
0
votes
0answers
35 views

Could my HF antenna cause problems to these other antennas on the roof? [duplicate]

I am planning to purchase a property soon in an apartment block on the top floor. I am very very keen to install a HF multiband Yagi antenna on the rooftop. I notice some small cell towers and a ...
2
votes
2answers
111 views

Erratic behavior on Baofeng UV-5R Plus

I bought a UV-5R Plus (8 watt radio in the same casing as a normal Baofeng), and I've noticed some strange behaviors. Occasionally when I key up on my local repeater, the radio turns itself off and on ...
2
votes
0answers
40 views

Any good RF noise "libraries" out there?

Are there any good/useful "libraries" of RF noise out there? I know about http://www.arrl.org/sounds-of-rfi but it is pretty limited. (And I wish the screencaps showed the FFT rather than ...
3
votes
1answer
189 views

Transmitted audio coming out through my speaker

I have a Kenwood TS590 HF transceiver. When I am transmitting and speaking into the microphone, I can hear my audio slightly coming out of my speaker connected to the radio (SP-23), or headphones if ...
4
votes
7answers
466 views

QRN: How to chase down a solid S9 noise floor on 40m only

I am new to this, having just set up my station. I have "very bad" QRN on 40m: S9. Here is the setup: High density suburb with flats and houses Yaesu FT450D with fan dipole at 6m-9m above ...
6
votes
3answers
2k views

Noise & shielding, SDR Dongle

First, I'm very new to SDR. This may turn out to be really obvious. I just want to verify my thoughts before I spend more dollars. I have a USB dongle with the RT28xx in it. Works great. Side by ...
1
vote
3answers
71 views

Ignition Static on 2m mobile but not 70cm

I have an ICOM 2730a 2m/440 mobile rig in a 2015 Ram 1500. Tx and Rx with truck not running is excellent. With engine running I hear static popping, but only on 2 meters. If I Tx I can hear the ...
1
vote
1answer
222 views

Need a ferrite suppression material for choking 15 kHz to 60 kHz

Electric fence RFI is ruining reception on our VLF lightning receivers, and we need a material to place around neighbors' fence wires to suppress the noise being radiated. Preferably, a split bead, ...
-4
votes
3answers
108 views

Can ham radio antennas interfere with RING devices, causing them to produce high-pitched noise? [closed]

Can a HUGE ham radio antenna on a house with an array of RING devices (5 in total) cause interference and high-frequency reverberation? The attached shows one of these devices (there's 2 under the ...
1
vote
1answer
51 views

What are the unintentional radiation limits in U.S. HF bands?

What are the radiation limits in U.S. HF bands in terms, not in terms of uV/M, but in dBm or uV levels transmitted though an HF dipole antenna? I assume that if the antenna is connected to a receiver ...
6
votes
3answers
2k views

How to stop interference on shortwave radio when connecting to a computer

I have a Tecsun PL-600 and when I can receive clear signals, and they come through just fine on headphones, and through the speaker. If I'm trying to receive RTTY or fax, when I connect the radio to ...
20
votes
2answers
11k views

How to detect common-mode currents or “RF in the shack”?

Let's say we already know that if your antenna is not suitably constructed or connected then you can get current on the shield of your coaxial feed line which will flow through the shielding/grounding ...
0
votes
1answer
65 views

What would cause 3 bursts of FM radio interference every ~3.5 seconds

I’m trying to locate the source of some interference on the FM band — it’s audible as 3 quick staccato bursts of brownish noise approximately every 3.5 seconds. It’s more pronounced at the low end of ...
4
votes
0answers
49 views

S Parameters in HFSS

I'm new to HFSS Software and I'm trying to plot Scattering parameters for a dielectric resonator excited by a probe (shown in image). I know that the top cylinder has a higher dielectric than the ...
0
votes
2answers
99 views

Can a slinky serve as a ferrite core and if so, is there a prefered configuration? [closed]

Ferrite cores ain't cheap when you start talking about the 3 inch ID ones. I can see em for like 40 and 50 bucks.... I don't see why I can't just ground a slinky or something.
4
votes
0answers
88 views

Checklist for QRO remote setup

In a few weeks I'm hoping to set up a solid state linear amplifier at a remote shack that I've set up at the house of a friend who lives in a rural area. I've been connecting to this shack remotely ...
0
votes
2answers
67 views

In most Solar Systems what causes more QRM on HF ham bands, the panels, the charge controller, or the distribution system?

Looking at solar systems Hams mention that solar often brings RFI into the system, what part of the system in most likely to introduce RFI detectable on the ham bands?
2
votes
1answer
93 views

Buzzing FM interference

What kind of interference or other receiver issues can cause a constant buzzing noise (picket fence lines in the audio spectrum) in the demodulated audio of a received NFM VHF signal? With AM, it ...
1
vote
2answers
652 views

High Noise Floor on 40/80m at Night

I've notice a couple of times over the past couple of weeks that the noise floor, particularly on 40 and 80, is exceptionally high as the grayline passes me into night. I'm looking at the general band ...
4
votes
6answers
617 views

Cordless phone consistently experiencing RFI

I've tried several cordless phones (most recently KX-TG570), and all seem to frequently pick up terrible RF interference. I have a neighbor that is a ham enthusiast, with large antenna masts on the ...
29
votes
6answers
35k views

Can I reduce RFI/noise at the antenna?

Recently, the power was out in my neighborhood for an extended period of time. I fired up my HF rig using battery power and was amazed at the lack of noise across the HF bands. When the power grid ...
2
votes
1answer
83 views

Reducing cross-band noise from plasma TV

I have a noise problem on 40, 20, and 15 meters originating from the plasma TV I own. Turning on the TV raises the noise level by 2–4 S units, depending on the frequency. The TV is located below the ...
7
votes
2answers
165 views

Apps and or equipment needed to document local interference?

A neighbor ham user recently started doing something that causes very noticeable feedback/buzzing in AM radio as well as any device that uses a wired microphone (such as a gopro with wired mic). ...
3
votes
2answers
134 views

Why am I receiving a local tv channel on a CMB frequency

I am using a simple Baofeng H6 dual band radio and I programmed weather channels. Well, on frequency 161.77500 I am actually picking up WGN, a local tv network. This frequency should be reserved to ...
0
votes
2answers
126 views

Identifying type of RFI by waterfall

I'm trying to identify the type of RFI I'm seeing on the waterfall in the picture below. It occurs mainly at night, every night, starting at about 6:30 p.m. and ending in the morning, and I have yet ...
1
vote
1answer
184 views

Can ham radio interfere with LTE wireless internet signal?

I know that there is another thread that asks a similar question however the questioner there had DSL internet, so I think my question is sufficiently different to warrant a new thread. (Can my ...
35
votes
14answers
34k views

Can my neighbor's ham radio antenna be interfering with my internet signal or is my internet provider just throwing blame elsewhere?

My internet provider is telling me that an antenna on my neighbor's house, which he called a ham radio antenna, is interfering with my DSL internet signal. I'm not tech savvy at all, beyond what's ...
2
votes
1answer
163 views

Unknown signal on 446MHz LSB (possible RFI?)

I am attempting to hunt down many sources of RFI in and near the UHF amateur bands at my home, but I stumbled across a very specific one that I have definitely never heard before. This one sounds less ...
0
votes
2answers
133 views

How should I go about finding the transmitter or antenna of a radio signal?

This site gets many questions about people trying to track down RFI, or interesting signals picked up on radios. Often the exact location of the transmitter or the antenna would be a valuable clue to ...
1
vote
1answer
75 views

Can sound generated by interference of cell phone signals contain any useful data?

When a cellphone is near an electronic device with speakers and someone's calling, we may hear a sound like this due to interference: Cell Phone Interference Sound Can we obtain any useful information ...
11
votes
3answers
2k views

How can I get rid of RFI coming from my house solar panel inverter?

The solar system on my house creates horrible rfi on all hf bands during the day when the sun is out, it goes away when it's not sunny. Any one got any ideas how to get rid of the rfi ? I already ...
2
votes
2answers
135 views

Building a low-power simple RF frequency (433MHz or 900MHz (but not both)) detector effective at 5m with a 10mW signal

I am looking for a simple schematic for building an effective RF detector which can trigger a GPIO. The goal is to (passively?) detect a 10 mW RF signal (10% duty cycle) and have that raise voltage on ...
2
votes
1answer
153 views

Receiving an Coded Odd Signal at 137.25MHz but don't know what it might be. It can affect my detection on NOAA 19. Need help

I am a newbie trying to detect NOAA 15, 18, and 19 satellites, which have downlink frequencies between 137 MHz and 138 MHz. I am using an SDR dongle and attached a photo of it to this post. Of course,...
5
votes
2answers
91 views

How does a digital demodulator know which level it is reading?

I have recently started getting into wireless digital communications and I read about QAM modulation. But I am a little confused as to how the receiving demodulator would know which symbol it is ...
2
votes
1answer
81 views

RFI from radials

Helping a friend with his RFI problem. He has a SDR HF radio and Hustler BTV antenna with a toroid choke and about 32-radials. He has vertical bars on his panadaptor around 20 khz apart, mainly on 40M....
1
vote
2answers
508 views

Hunting RFI with bars every 61 khz

I realise there have been many great posts on hunting RFI, i've got pretty close to tracking mine down, but would appreciate some insights from the ham.se experts :) I've done quite a lot of work to ...
3
votes
5answers
1k views

Do chokes at the antenna feedpoint stop the coax from receiving signals as well, or just transmitting?

It seems common knowledge that a choke at the antenna feedpoint stops the outside of the coax shield from radiating when transmitting into the antenna. But what about stopping the outside of the coax ...
1
vote
1answer
118 views

What is the maximum antenna cable length allowed in GNSS application?

I am beginner in designing GNSS receiver design and facing concern while testing the high precision GNSS survey.I am using GNSS survey grade antenna for my GNSS receiver application testing, the ...
1
vote
3answers
111 views

What is the name of a device used to detect noisy appliances?

I live in an apartment. I don't have control over all of the appliances but perhaps I can mitigate if I know where the noise is coming from and under what circumstances. If I'm shopping for such a ...
3
votes
2answers
264 views

What kind of RFI is this?

I'm getting a lot of noise now that I have a dipole higher up. The pattern on the waterfall makes it seem man made. Could it be power line? Or is it some kind of motor? Here's a short video of the ...
0
votes
2answers
88 views

How Duty cycle affects transmission rate in RF module?

I planning to use RF module for communication of high precision GNSS module. So I am doing detail study on RF module. In one of the datasheets of RF module (part no: RFD868ux) mentioned that 'Duty ...
11
votes
2answers
4k views

How to reduce RF in the shack when using vertical HF antenna (no radials)

What can be done to reduce RF in the shack (riding back along the coax) when using a vertical 10M antenna (without radials due to space constraints)? The antenna is an IMax-2000 at 32' elevation (20' ...
5
votes
2answers
587 views

Using an SDR on a Laptop with Noisy Power Supply

I'm going to start this off by saying I'm very new to this and I don't really know a lot so any detailed information would be much appreciated. I have just started using an SDR (a cheap RTL model) ...
3
votes
3answers
105 views

Method to generate PIM

I would like to have a go at measuring PIM. ( Passive Intermodulation ) in UHF. To test my ability to measure PIM, I need to find something that generates PIM. I either envision a 50Ω device that ...
3
votes
0answers
284 views

The whole neighborhood's internet drops when I transmit on 40M

I recently built a vertical. It's 6M radiator, a coil, and 1.2M more of radiator. It sits on my roof, which is metal, and acts as a ground plane (GND from the feedline is connected to it). There is a ...
3
votes
2answers
1k views

How does FM station have fixed frequency when FM modulation changes the frequency?

I am not sure if this question fits better in physics.stackexchange or ham.stackexchange, feel free to correct me. I am new to studying RF and SDR in general, I was looking up how modulation works and ...
10
votes
3answers
2k views

My neighbor is complaining about my transmissions, what can I do?

My neighbor has indicated that they can hear noise from their computer amplified speakers when I'm transmitting. We've done a few tests and it does appear that it's my transmitter that's causing the ...
5
votes
2answers
416 views

Wide band TX capable band-pass filter for VHF and Airband

I want to share the same antenna for VHF (TX/RX 144-148 MHz) and for Airband RX-only (116-136 MHz). I live on a very congested area where filter is a must, so I'm looking for the best solution for my ...