Questions tagged [am]
The am tag has no usage guidance.
34
questions
2
votes
1answer
151 views
Simple AM Radio Troubleshooting
I just got all the parts to make a simple AM transmitter from Scitoys. I followed the instructions from different websites and they still don't work. I don't know why it's not working. On my ...
2
votes
2answers
344 views
Broadcast signal deviating with time
I've been just scanning through the HF band at night seeing what all I can pick up, and I'm trying to figure out a particular signal. I'm using a VHF discone, which isn't ideal, but it works well ...
1
vote
3answers
89 views
Radio Waves propagation (Intuitive Understanding of Wave propagation)
I have few similar questions regarding Radio waves communication particularly FM and AM type of Radio wave communication. Please bear with the naivety of the questions.
Questions:
Radio waves in FM ...
4
votes
1answer
73 views
AM Radio Envelope Dectector
How do you choose the values of the capacitor and the resistor in an envelope detector circuit? In my case, the frequency range is from
20 Hz to 20,000 Hz. Also, am I correct in understanding that ...
-1
votes
3answers
81 views
Recommended Books For AM/FM (especially AM) Radio Design
I am trying to gain a better grasp of how to build an AM radio receiver. Can you direct me to some books (or other information) that will help?
1
vote
4answers
194 views
Building an AM Radio receiver
I am making an AM radio with the specifications of: Part 1. Design a circuit with an antenna for tuning your receiver to a signal of a specific carrier radio frequency so that you can select a certain ...
-3
votes
4answers
125 views
Transmitting as SW AM station, not ham [closed]
What if I wanted to run a radio broadcast station on a commercial SW band? Say, I am on a boat in international waters. Or say I am in a free country. I monitor the frequency for months and I check ...
2
votes
1answer
79 views
How much field strength to blow out a receiver?
I was wondering what calculations would need to be performed to find out if a receiver will blow out in the given conditions.
Portable AM receiver with ferrite rod antenna 200 ft away from MW antenna ...
3
votes
1answer
178 views
I/Q demodulation of DSBSC-AM signals
I was looking at some Stereo FM demodulators on the Internet, and I can't understand
the use of the complex to real block for demodulation of the L-R signal (DSBSC-AM)
which can be seen in different ...
2
votes
3answers
374 views
Improve AM reception on an old Walkman that has no external antenna
I have an old Philips walkman that has AM/FM radio. I tried AM radio. Really I can get clearly 2 country radios. I catched very poorly 4 foreign radios or different countries, but they do lots of ...
0
votes
3answers
163 views
How to make simple AM detector using an LED?
I'm new to amateur radio, and as a beginner project, I wanted to use some of the basic components I have to create an AM receiver.
Anyway, what I'm trying to do is create a simple AM receiver that ...
2
votes
2answers
70 views
Daisy Chaining AM filters to help with IMD
I live near an AM transmitter, and the input of my RTL-SDR becomes overloaded. I've added an AM filter and it's really helped, however I still get a very strong AM signal with some IMD all over ...
2
votes
2answers
960 views
Why does a Class-C non-linear power amp distort SSB but does not distort AM?
Can someone tell me why exactly a transistor non-linear power amplifier will amplify an AM signal without noticeable distortion, but will distort an SSB signal, giving the familiar scratchy sound ...
3
votes
2answers
95 views
Mobile 2m / 70cm dual band with aviation frequency TX capability
Forgive what may be a basic inquiry from a new enthusiast. I am new to amateur radio, just barely passed Technician and General tests. I am also a pilot and have an RR class licence. I believe that I ...
16
votes
3answers
4k views
Why do we not use AM and FM at the same time to transmit more information?
Amplitude modulation uses the modulation of the amplitude of a carrier wave to transmit data while leaving the carrier frequency constant, and in the case of FM it's just the other way round.
Why is ...
1
vote
1answer
145 views
Is there any way in which elevation *does* affect medium frequency (AM radio) transmissions?
This is a followup to this question of mine. From reading the wiki article, I get that:
Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere ( called skywaves)...
3
votes
3answers
322 views
78.5MHz AM receiver self-oscillation
Circuit appears to be working but very easily breaks into oscillation - sometimes just getting up from my desk triggers it, or while tuning, and sometimes after a few seconds with no disturbance that ...
1
vote
1answer
106 views
BFO locked synchronous AM detection
I am fixing up an old classic Yaesu FRG7 general coverage AM/SSB/CW HF receiver. The BFO section is a rudimentry 455 kHz IFT configured as a carrier reinsertion oscillator that that is made to run USB ...
0
votes
2answers
201 views
Peak envelope power should be 2:1 or 4:1 on meter?
I've always been reading my AM modulated signal on a Bird wattmeter and trying to set the carrier to 1/4 of the peak envelope power (PEP).
Recently, I was told by a CBer that you only can see it that ...
2
votes
1answer
43 views
Poor reception on single AM channel
My car stereo has terrible reception on a single AM station. Other cars get the signal fine and other channels on radio are received fine. I have contemplated some sort of booster for the antenna or ...
1
vote
1answer
67 views
Why AM modulation side bands have higher frequencies than the carrier?
I cannot understand while the AM modulations have sidebands which are of a frequency higher than the carrier. If for example we are modulating a 4kHz signal to a carrier of 1MHz how we end up with a ...
3
votes
1answer
891 views
Why does the output power of some AM transmitters increase when modulated and of others decrease?
I didn't fully understand all the finer details of AM, so I'd like an explanation for the following behavior:
I have 3 radios. In AM mode, one of the radios, when modulated, increases output power ...
2
votes
1answer
175 views
How does this circuit work? Why is the antenna connected to the output of the amplification stage?
What is the function of the configuration of R1, C3,C10 and R3? How does the LC tank in this circuit work?
10
votes
1answer
1k views
Is FM modulation still more resistant to noise when given the same bandwidth as an AM signal?
FM modulated radio is much more resistant to noise and can deliver better sound quality than AM radio. But FM signals also use more bandwidth than AM signals. In general a wider bandwidth signal is ...
4
votes
1answer
2k views
Building a crystal radio with my brother. How does this circuit work?
I'll be visiting home soon after school lets out, and I want to build an AM crystal radio with my little brother. This is the design we'll use:
http://crystalradio.net/beginners/
I'll be doing my ...
2
votes
1answer
104 views
MW AM reception improvements?
Most AM receivers use Envelope detection. Historically this was simple. PLL-based systems are slightly better at low carrier-to-noise levels. Would there be any SNR advantage if each sideband was ...
2
votes
1answer
117 views
feasibility of wireless passive crystal earphones
I just learnt about such a thing as a crystal radio receiver and the following idea came to my mind. I have no background knowledge on electronics nor anything related.
What if battery-less earbuds ...
3
votes
1answer
2k views
Why are FM radio waves less susceptible to interference than AM?
When studying modulation of radio waves (or of most electromagnetic waves for that matter) I came across this question:
Why are FM waves less susceptible to interference than AM waves?
I know that ...
1
vote
1answer
166 views
Reception for FM stations is offset, but AM stations aren't
I have a Realistic STA-78 AM/FM Stereo receiver I recently rescued from my grandmother's attic. It hadn't been played in a while, but it appears everything is in working order except the FM dial. It's ...
9
votes
1answer
467 views
Why does AM have sidebands?
Why does AM have sidebands? Isn't the whole point of AM to broadcast on ONE frequency and ONLY change the amplitude?
In the picture there is only ONE frequency and the amplitude changes, so why ...
3
votes
6answers
2k views
Would it be feasible to set up a SSB or AM 2 meter repeater?
Would it be feasible to set up a SSB or AM 2 meter repeater? I want to set up an AllStar full duplex node and like the idea of AM because stations can double without issues. SSB works for weaker ...
4
votes
0answers
83 views
Why the value of IF of AM is 455 kHz? [duplicate]
Why the value of intermediate frequency (IF) of amplitude modulation (AM) is 455 kHz? Why not another value?
6
votes
2answers
186 views
What happens when I and Q are switched?
In https://ham.stackexchange.com/a/1068/9 it's shown that one can use
$$ r = \sqrt{I^2+Q^2} $$
to decode AM signals from a direct conversion receiver. It appears that, in this particular case, I ...
5
votes
5answers
2k views
Simple DIY AM receiver for 25/28 MHz
I'd like to build a simple AM receiver for 25 and/or 28 MHz to receive DCF77-formatted time code. It doesn't have to be extremely sensitive or selective - the local clock oscillator will keep time ...
