Questions tagged [bandwidth]

Questions about bandwidth used by various modes, theoretical questions about bandwidth, and questions about other amateur radio aspects of bandwidth.

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Is Gnuradio `file sink` data time domain data or frequency domain data?

When I enable file sink,I could save and read data of Gnuradio as below: Questions as below: 1.Is the file sink data time ...
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1 answer
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Help synchronize on unknown frequency sequence

I am having trouble to synchronize on a frequency hopping pattern between an emitter Tx and a receiver Rx. More precisely, the ...
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1 answer
59 views

Weird looking spectrum. FSK and ASK combo?

Does this look familiar to anyone ?
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2 votes
2 answers
114 views

What's the difference between LPF and BPF in context of bandwidth setting?

I'm used to simple RX/TX bandwidth configurations, on my VHF FM rig it's either narrow, normal, or wide. It seems to be much more complex on my new HF SDR rig, and the instructions don't say anything ...
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7 votes
1 answer
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Why ferrite-core transformers are wideband while air-core are not?

While experimenting with end-fed antennas I've made two 1:49 transformers. The first one has an air core, as shown in the article by John, M0UKD. This transformer doesn't even work as a transformer ...
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2 votes
1 answer
114 views

Coupling Capacitor of an Antenna

I have a simple question about general meaning & importance of the coupling capacitor in following part of a simple receiver circuit: Is it true that the proper reason why this coupling capacitor ...
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3 votes
1 answer
71 views

Calculating SWR for a dipole

I have a dipole wire antenna that is tuned to 14.0 MHz so that it has an SWR there of nearly 1:1. Is there a mathematical formula by which I can compute the expected SWR for other frequencies? I would,...
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1 answer
67 views

Does signal frequency affect the band width of SDR hardware?

I am new to SDR,already owned USRP B210 and start to learn Gnuradio. I have follow question: B210 has max bind width 56Mhz.When I use max sample rate to received signal,does the signal frequency(...
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5 votes
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Gnuradio bandwidth of sink cause signal frequency changed?

System is debian 10 with gnuradio 3.7. untitled.grc create simple flow graph as below: The only difference between 2 flows is bandwidth of gui sink,cause 2 ...
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How to Measure Bandwidth using just your receiver [closed]

How do you measure the two to one bandwidth of an antenna using a Bird Watt meter? Tom Planer KJ9P
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3 answers
208 views

Why do PSK modes have "bandwidth"?

My understanding of a naive PSK scheme is that you have some frequency(s), f(n), at baseband, and you modulate information by shifting the phase (what "point in time") the signal is at. Isn'...
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2 votes
3 answers
215 views

How do 'plumber's delight' type Yagi antennas have a bandwidth?

For Yagi antennas where the driven element is electrically connected to the boom like the parasitic elements, how can this function without diminished performance outside of the design frequency? In ...
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1 vote
0 answers
38 views

Labview Spectral Monitoring (USRP) - Bandwidth expansion and frequency change

I connected USRP (together with antenna) to my computer to receive some signals. For this purpose, I used the built-in module "Spectral Monitoring (Interactive)". Unfortunately I noticed ...
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1 vote
2 answers
226 views

What does antenna frequency range mean in practice?

I'm trying to wrap my head around software defined radios and antennas and noticed that lots of antennas are described in terms of a frequency range. For example, this one is described as operating ...
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How to increase the bandwidth of half-wave dipole antenna?

I have designed a half-wave dipole antenna for frequency range of 150 to 200 MHz. Due to resonant frequency of 175 MHz, Its dimensions are: L=817.44 mm, R=1.71 mm. Impedance is also equal to 73 ohms. ...
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3 votes
2 answers
413 views

If the data port on a Yaesu FT-7800R only communicates FM signals, why does the manual mention the port having a bit rate?

I was wondering how the Radio interfaced with a TNC. I thought the computer sent digital data (in a serial format) to the data port on the radio, but from what I read online, it is not a data port. ...
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4 answers
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Determining one exact antenna length for a whole band (e.g. FM/AM broadcast, Bluetooth and others)

How does a single FM antenna length work in the entire FM frequency band range, when there are theories which state that the antenna size should always be close to wavelength/4 for proper reception &...
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2 answers
463 views

Power vs. Bandwidth

A 10 watt transmitter is transmitting a 700 hz tone in a 3 kHz wide band. If the power is increased to 1000 watts will that not increase the bandwidth if the data (700Hz tone) remains constant? What ...
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3 votes
3 answers
1k views

NFM and FM compatibility

I read that using narrow band (NFM) when you should be using normal(FM)/wide-band(WFM) can result in the a reduced volume at the receiver. What happens in the opposite situation? (What if you are ...
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Maximum legal QRQ CW speed?

Computer generated and decoded Morse Code seems to be a not-uncommon operating practice in the HF bands. Given this, and that there's no reason why Morse/CW signals can't be synthesized and decoded ...
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3 votes
1 answer
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Is it possible to receive weather satellites with a ham radio rig? (Icom 910)

I would be interested in receiving weather satellites (NOAA and Meteor) with my Icom 910. It has very good filters and could be a better solution than a simple SDR. However, its manual specifies that ...
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1 vote
2 answers
142 views

If I parallel two crystal filters together, will that double the bandwidth? [closed]

Will the bandwidth be doubled ? And will the impedance be halved ?
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5 votes
4 answers
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How does a receiver know the exact frequency in the channel to "listen to"?

I am reading about how radio communication works and I have an unanswered question. We have wideband channels with 25kHz of radio spectrum. The transmitter modulates a signal and sends it. The ...
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1 answer
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3 Band (80-40-20 Meter) Fan Dipole Tuning Question

I built a fan dipole according to the basic instructions in the SRI publication describing the theory and basic design. My questions is about next steps in tuning for the various bands. I am ...
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8 votes
2 answers
2k views

How does signal strength relate to bandwidth?

Let's say I have a 25 W transmitter. First I transmit some SSB signal with 2500 Hz bandwidth (no audio compressor is used, etc...). Then I transmit a BPSK31 signal with at most 100 Hz bandwidth using ...
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8 votes
1 answer
282 views

Why are radio frequency ranges aligned on multiples of 3?

Why are the radio bands organized by multiples of three? For example the HF band is from 3–30MHz and UHF is from 300–3000MHz. Why not multiples of 2? Or plain powers of ten?
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9 votes
2 answers
422 views

Why do the ham radio bands get broader with increasing frequency?

The ham radio frequency allocations tend to comprise a larger frequency range for increasing frequency (also see this plot). For example, the 40 meters band is from 7,0 to 7,2 MHz, thus 200 kHz, while ...
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What is the equation relating maximum data transfer rates for a given EM bandwidth

I was thinking, since visible light has a much higher EM frequency than radio wave light, its bandwidth also has a far higher max data transmission rate, so people have been researching how to use ...
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Ultrasonic FM receiver

I need a FM receiver that is capable of receiving ultrasonic audio frequencies above the standard wide band FM range of 15 KHz. I'd like something that can receive signals up to 60 kHz if possible: I'...
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10 votes
2 answers
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Do FCC regulations limit digital data rate?

Are there FCC regulations that specifically limit digital data rate on the amateur bands? Are there any recent or proposed changes? If so, what are they specifically?
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6 votes
1 answer
1k views

Is there a legal limit to the bandwidth of a signal used in the amateur bands?

While a normal voice channel is ~10kHz-15kHz in bandwidth, some digital modes can be significantly wider. Are there any legal restrictions on how much bandwidth I could use for amateur radio ...
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2 votes
1 answer
110 views

Channel Bandwidth & Occupying Frequencies

I have started working on TDMA algorithms for SDR utilizing narrow band waveforms, and I have started reading about narrowband waveforms. But I am confused about the concepts of channel bandwidth and ...
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11 votes
6 answers
657 views

Key CW on zero crossings - zero bandwidth?

I remember being surprised to learn that a CW signal has a bandwidth (albeit small), but when I thought it over, it made sense. Essentially, we are modulating the carrier with a low frequency square ...
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4 votes
2 answers
885 views

Sound quality in portable FM radio devices vs dedicated stations

When speaking to a portable radio transmitter the sounds usually gets distorted. However in radio stations that are dedicated to play music the sound is significantly better. First of all, why? And ...
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1 vote
1 answer
262 views

How to generate FM narrowband using varactors

I don't really understand how FM narrow band is created, and at the same time I can't figure out how using this simple circuit of varactors (varicap diodes) we narrow the bandwidth. simulate this ...
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9 votes
2 answers
1k views

Moon->Earth 433MHz link achievable digital bandwidth

Let's assume we have the following situation: Transmitter on moon orbit (distance from earth ~400'000km), around 433Mhz. Transmitter power 1W, antenna gain 10dB, circular polarization. Steered to ...
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1 vote
1 answer
101 views

overly large bandwith for a FSK signal?

I am trying to recover my 2FSK signal using an SDR. I have centered the SDR modem on the median frequency (the virtual carrier) and captured my signal via some 90 kHz bw modem. THis is the recording ...
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11 votes
1 answer
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Why does the FCC put restrictions on symbol rates?

This answer claims that Mostly, on HF, the FCC has chosen to limit modes of transmission and symbol rates rather than bandwidth Why does the FCC limit symbol rates?
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1 answer
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What are the standard bandwidths used on the various amateur bands?

What are the standard bandwidths used on the various amateur bands? For example, FM on 2 meter generally uses about 3kHz, right?
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2 votes
1 answer
658 views

What are the FCC's bandwidth restrictions for the various amateur bands?

Does the FCC restrict how much bandwidth an amateur radio operator can transmit? I've seen restrictions for transmitting data, like packet and ATV, but, for example, could I legally use a huge ...
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5 votes
1 answer
720 views

Does the wire/conductor size of all the elements affect antenna bandwidth?

Does the wire diameter of the reflector and the directors of a beam antenna affect the bandwidth or is it only the driven element diameter that has this effect?
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1 vote
1 answer
1k views

Do reflector and director widths (wire size) affect Quagi bandwidth?

A 2m Quad antenna made from 1/2" tubing will have a larger bandwidth than the same Quad built with 14 AWG wire. Would the respective bandwidths be maintained if both Quad loops were made into Quagis ...
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4 votes
1 answer
4k views

How many frequency channels are there in a frequency band?

I've often heard people saying that 4G uses the 1800 MHz band but precisely what all frequencies does it work upon? Does it mean that is just uses one frequency i.e. 1800 MHz, well in that case wouldn'...
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5 votes
1 answer
312 views

Receiving commercial / public-safety on a general-coverage HAM transceiver

I have an ICOM-7100 that I've installed in my mobile as my primary (nay, only) HAM transceiver; and I'm trying to avoid wasting a ton of space in my vehicle (not to mention money) for a proper scanner,...
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3 votes
3 answers
7k views

Calculating bandwidth of antenna?

Is there a way to calculate bandwidth of an classical dipole antenna having this information: center frequency wire velocity wire diameter I would disregard antenna height, to simplify. I am not ...
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3 votes
1 answer
177 views

What is the proper spacing away from a rare RTTY station?

How far away should I transmit from a rare DX station in RTTY? RTTY itself doesn't take that much bandwidth, but I've heard that I should be spaced 2-3 kHz away. Is that true? Thanks!
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1 vote
3 answers
430 views

Bandwidth, Q-factor, Radiation Eff calculations

Is it possible to give approximate answers about what an antenna is capable of? There are a lot of formulas out there, but every single one I found is based on actual measurement; input, output, SWR ...
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3 votes
2 answers
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Is it possible to calculate the Q factor for an antenna type, given a frequency?

With only pen and paper, is it possible to calculate the ideal Q-factor for e.g. a dipole antenna, loop etc, given a frequency?
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12 votes
3 answers
719 views

What are the relative bandwidths of the amateur bands?

While I was operating on 40 m for Field Day, I noticed a higher SWR than when I first set my antenna tuner for the band. This happened, of course, because I was in a different part of the band, but I ...
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2 votes
1 answer
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ISM band bandwidth compared to other bands for theoretical WLAN use, performance?

As a purely theoretical question, what would it be like if wireless computer networking equipment was redesigned and allowed to operate at some other band than the unlicensed ISM band which is ...
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