Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [superheterodyne]

15 questions
12
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7 answers

Why is superheterodyning better than direct conversion?

What is the advantage of having the extra stage of IF, extra local oscillator and extra filtering stage and amplification. It just seems like more work and circuitry. Surely the direct conversion to baseband and the intermediate conversion to…
Lewis Kelsey
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2 answers

What is the reason behind the wiring of the IF tapped transformers in these AM superheterodyne receivers?

I'm going through R.Quan's book "Build your own transistor radios", and I'm triying to build one of his simple AM superhet receivers. Since it offers many working schematics, the book is very interesting from the point of view of a novice - which I…
Dag
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Intermediate frequency

I'm a newbie to communication systems and circuitry. I was going through superhet receivers while trying to undertand AM/FM/DAB receiver architecture. For FM, IF is fixed to 10.7 MHz and AM 455 KHz. Once the carrier wave is shifted to this IF…
Gomu
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Can a non-modulated / continuous carrier be heard in Superheterodyne receiver? Why do we need BFO?

I think a continuous carrier be able to heard in a super-heterodyne receiver, since it has it's own oscillator. Why do we need BFO then? What's the difference between the two? So, morse codes would be heard just on super-het receiver?
Sachin Chaudhary
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SuperHeterodyne receiver

In a superheterodyne receiver, let us assume, I have a signal in the RF range of 88MHz to 108MHz. From what I have read, my understanding is that by tuning the local oscillator frequency, we can make the incoming RF signal to fall within the IF…
user220456
1
vote
4 answers

Substitute for 455 kHz Ceramic filters in new designs

I was wondering what has ever happened with the 455 kHz ceramic filters commonly used in the second IF stage of a superhet radio receivers? All but just a very few (and those left over don't seem to stock them anyway) don't manufacture anymore and…
citizen
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In heterodyn receiver circuits, why is the LO not chosen to match the target frequency?

I'm trying to design a device that detects motion using sonar. I'm basing it on a common superheterodyne receiver like this: Now from what I've read, in radio audio receivers the local oscillator is chosen to be a specific offset from the target…
Drew
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Solving an exercise of superheterodyne receiver with high IF frequency

I've been struggling with this problem for several hours. I have a high IF superheterodyne receiver. The input frequency can vary from 9kHz to 3GHz. I need to calculate the minimum intermediate frequency (f_IF) if it is being used an IF filter of…
neil_huygens
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NOAA satellite RF superhet receiver - local oscillator frequency precision

I am currently designing a RF receiver for the APT protocol in order to collect NOAA weather images. This has been widely done on the internet, but I'd like to do it from scratch and not use any SDR. I've come up with a superhet receiver followed by…
Clément Chaine
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Superhet Receiver

I'm at best a hack EE but I'm attempting to design a 20 meter receiver for learning reasons. I have settled on a superhet and I'm trying to avoid looking at existing designs, the struggle helps my understanding I find. I'm not attempting to build…
foreverska
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Superheterodyne receiver channel selectivity

I have quite simple question about topology of superheterodyne. I am facing with adjacent channel selectivity problem. The problem is that I can't obtain selectivity more than 40 dB. F.e. when wanted channel frequency signal had ampl. level 1 dBuV…
Fasset
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Bandwidth-Noise-SNR relationship

Let’s say we have the noise figure F of a system of devices. We also have the bandwidth improvement coefficient ( as defined by my teacher ) $$BI=10log(\frac{B_{in}}{B_{out}})$$ where B1 is the bandwidth at the input and B2 the bandwidth at the…
John Katsantas
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direct conversion SSB (vs DSB-SC)

While I understand the problems trying to demodulate a DSB-SC signal using a direct conversion scheme, mostly the phasing issues arising from the fact that the sidebands are symettric and in quadrature, I still don't get why SSB receivers can't just…
Angel
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Superheterodyne and intermodulation products: understanding f_RF-f_LO Graph

While studying superheterodyne-based spectrum analyzers I ran into the concept of intermodulation products explained through a \$f_{RF}-f_{LO}\$ graph. If it's not clear enough, the dashed lines are simply references \$f_{RF}=kf_{LO}\$ (\$k=1,2\$),…
DavideM
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Spectrum analyser

Why do we use ramp generator (sawtooth generator) with local oscillator in a spectrum analyser? I have searched in Google and I didn't find any answer that made me understand the concept. Thanks !
Sri Harsha
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