Questions on a set of equipment used to generate and transmit electromagnetic waves carrying messages or signals, esp. those of radio or television.

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1answer
83 views

Help with a RF reciever circuit

Recently I have been working on a basic RF receiver, but my efforts so far have proved fruitless. I designed the following circuit based of of previous research into the topic. According to what I ...
2
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1answer
52 views

A question about resonance and crystal radio?

This is a circuit of crystal radio transmitter. I've tested it, and it works properly. but I can't understand everything in this circuit... L1 and C5 make resonance frequency, Would you tell me if ...
1
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1answer
107 views

Basic FM circuit

I have been messing around with a basic FM transmitter circuit, and I want to have a better explanation on how it works. I have searched around and found nothing. Can someone please explain how the LC ...
0
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1answer
43 views

FM Transmitter Amplifier — Maximum output power with non-customized parts?

I would like to build an FM transmitter on my own and I found a nice circuit that acts as a USB sound card to transmit low power FM signals. http://tipok.org.ua/node/35 My plan is to add another ...
7
votes
7answers
278 views

Measuring direction of object (or angle of signal origin)

I am interested in somehow tracking the "compass" direction of a moving object from a reference-station -- in other words, something similar to submarine sonar systems (although I'm unsure how those ...
1
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2answers
88 views

How can I turn pulsating DC (square wave) from a 555 IC timer into an ac square wave?

I am trying to create build a morse code transmitter. I know that morse code is sent at 500 KHZ so I set my 555 to spit out pulsating DC in a square wave with 9 volt peaks. But I am unsure wether ...
8
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7answers
1k views

Schematics for a simple radio transmitter that can be built only with passive components?

Fantasized in some of the survivalist, post-catastrophic novels, movies or docudramas is the radio built only with handcrafted or scraped components. Beyond the popular appeal of this stories, I ...
4
votes
1answer
546 views

Data over a 5V DC power connector

I am looking for a simple way to encode some data over a dc power line. (Probably using a very low cost IC) In my design, I have a port that provides 5V, 200mA for connecting some device, but now I ...
0
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1answer
22 views

Could transmit/receive turnaround be improved by having a heterodyne receiver switchable between high-side and low-side injection

In some of the small radios I've worked with such as the Nordic Semiconductor 24LE line, there is a significant (100us+) delay between transmitting data and being able to receive a response. By my ...
0
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0answers
69 views

PIC16C54 used as signal generator from 100 KHz to 180 MHz

I have a PIC16C54 used as a DDS which generates 100 KHz to 180 MHz sine waves, model #80-035 datakit , I need source code but company is out of business. I purchased this as the early model called ...
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1answer
59 views

Separate antenna for radio transmitter and receiver

I am building a HAM radio. Do I need a separate antenna for transmitter and receiver? I will be using 20m band and voice communication (No Morse code). My primary requirement is that I should be able ...
1
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1answer
107 views

How do I sniff this RF Transmitter Gate Opener Circuit?

What piece of hardware am I looking for to observe the transmitted radio signal? Would an oscilloscope come in handy here? is this a 2-channel RF remote, a 3channel RF remote, or something else? My ...
1
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4answers
98 views

How do multiple transmitters and single reciever work?

I have multiple digital transmitters sending packets to an receiver, and packets from different transmitters may arrive at the same time, how can the receiver differentiate multiple packets at the ...
1
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0answers
644 views

Audio + Video Transmitter + Reciever With 5 - 10 KM Range Circuit Diagram [closed]

I'm looking for a circuit diagram for a audio (doesn't have to be stereo) with video transmitter and reciever that has a range of more that 5 kilometers. I don't really have any limits on power ...
1
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3answers
123 views

Radio frequency signal transmitter

I lost the remote of an RC helicopter. I want to make a remote and know about the circuit. I am searching for this component which has three legs beside the LED in the pic. Would someone help me ...
1
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1answer
150 views

How to find out what radio frequency is being emitted?

Let's say I have something akin to a garage door clicker. How can I discover the frequency and message it sends with no other information on the device? I want to decode this to the electrical ...
0
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1answer
100 views

Need a help with 3D Low Frequency Wakeup Receiver AS3933

I am software developer and I am totally new to circuits field. Can somebody help me to understand how the 125 kHz transmitter and AS3933 receiver works? This is the link where it says how it ...
0
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0answers
114 views

How to switch a transistor when a radio signal is received?

I have a circuit which switches on by sending current to the base of one of its transistors. I'm trying to make receiver which can receive signals from a AM transmitter and send current to base of ...
0
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1answer
70 views

Can we capture and reproduce the bluetooth signals

Are there any devices that can capture bluetooth signals and reproduce them? Or is it simply possible to capture bluetooth signals if we have any bluetooth device? Does a bluetooth device have ...
0
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1answer
514 views

Power LED's using RF transmitter and receiver with Arduino

I'm working on a project that I have two sensors, two Arduinos (a YUN and an UNO), two LED's, and an RF transmitter/receiver It's a pretty simple procedure: Activate a force sensor, send it via RF ...
2
votes
1answer
177 views

How does a cube sat communicate with ground station with a 1w antenna

I heard that cubesat signals can be received with a hand held radio. Its confusing me that how a 1 metre antenna radiating 1watt energy can simply be received using hand held radios. I am designing a ...
1
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1answer
80 views

Can I estimate Wi-Fi's power transmission in function of the amount of data transmitted?

For a specific device connected to specific AP. Can I estimate the differences in radiation power (mWh) depending on the data transmitted (2KB/s vs 200KB/s)? If so, how?
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2answers
160 views

Hardware advice for simple wireless embedded application

Now, I am going to learn embedded programming in microcontroller. I am going to create a device that will receive signal from wireless transmitter. The range will be less than 30 meters. So, I have ...
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0answers
90 views

Bluetooth receiver from multiple transmitters

I need a bluetooth receiver to receive a signal from few transmitters. There is extremely little information about bluetooth on the internet. Google gives a lot of topics about android and iPhones, ...
0
votes
3answers
142 views

Linear potentiometer for suspension travel

I am working on a project for university measuring the extension of a cars suspension. I have a potentiometer available to me, but have a few questions regarding how to use it. I understand that it ...
1
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1answer
195 views

Using RF Link Transmitter/Receiver - ADC vs Microcontroller?

I have a sensor that gives off 4 volts when actuated and I would like to transmit it a distance to a light. So I found these RF Link Transmitter/Receiver at 434MHz: ...
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1answer
378 views

FM transmitter main output frequency

please tell me the output frequency of this circuit,its work and has about 10 watt power with using C2101 as output stage,thanks It's working,and has high power in so far as I turn it on close to ...
0
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2answers
89 views

How to increase frequency modulation index?

I'm thinking of making a low power FM transmitter. Here's a diagram. It seems an absolute pull range of a VCXO will limit the modulation index. Is there possibly a way to extend it?
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1answer
169 views

Trying to figure out the distance my computer is from my Bluetooth peripheral via RSSI. Is it possible?

I'm having a great deal of trouble figuring it out. I know it's far from exact, but I would like to have a reasonable estimate in meters. Right now my device is reporting back to my the RSSI value ...
0
votes
1answer
97 views

Can a smartphone transmit over the 902-928MHz bands? [closed]

I came across a remote control that uses the 902-928MHz band. Can a smartphone transmit WiFi/Bluetooth over those frequencies? If yes, is there anything special about it? Thanks
3
votes
2answers
139 views

Determining type of modulation

The circuit below is a radio transmitter circuit of a typical RC car. The circuit makes use of IC TX2 encoder. The output of IC ("SO" pin) is a series of pulses at low speed (84 Hz). This signal will ...
1
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2answers
113 views

Why is it so hard to get waves through the earth and ocean?

Quoted from the source Crystal sets to Sideband, the author said if you have an ohm meter measuring across the whole earth, the meter would display only 300 ohms. A while ago, I asked about earth ...
0
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1answer
318 views

UHF Transmitter - Arduino - How to

I am planning to do a near space balloon project with my son. I want to do something special. I don't want to just send up a camera I want to broadcast live video and other metrics. I have a strong ...
0
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1answer
399 views

Using 27MHz car with 49MHz remote control

I managed to do something like this guy here, but after I connected the Arduino to the 49MHz remote control, I figured out that I have another car which works on ...
2
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2answers
79 views

Wireless signal reflection

When two devices are connected via wireless, one device sends a character using its TX line, and the character is received by the other device on its RX line, and vice versa. My question is, RF ...
2
votes
1answer
112 views

How to debug a transmitting configuration?

I'm using a CC1101 radio to communicate with an existing protocol. The settings I've used to configure the radio seem sound, as I'm able to receive messages from the 'other end' without errors. My ...
2
votes
1answer
262 views

Amplifying the signal from a transponder detection loop

Transponder I have a simple powered transponder which sends data using binary phase-shift keying (BPSK) on a 5Mhz carrier with a required range of 6-12 inches. It is used to time laps of remote ...
1
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2answers
144 views

Re-broadcasting a wideband satellite television signal over a short distance?

Normally a coax cable connects a satellite dish to the receiver. I'm in a situation where I can't easily install a coax cable, but a wireless signal ought to be possible because it's only 10 meters ...
4
votes
1answer
339 views

What is the advantage of differential Manchester

I can see the advantage of Manchester code over NRZ: you get clock and data in one signal combined. But what does differential Manchester add to that?
0
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1answer
41 views

Calculate transmitting power of the Transmitter

I cannot get a hold of my professor and I'm stuck tyring to understand how to solve this problem. It's not homework or an assignment I'm preparing my self for a test. So as the title states I need ...
1
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2answers
1k views

Using one RF transmitter to send an On/Off signal to multiple receivers

I want to create a system where I can send an On/Off signal to multiple receivers, to say, tell them to turn on an LED. Would I need to have a transmitter/receiver pair for each LED, or can I just ...
1
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2answers
1k views

Any wireless technology to find the distance between transmitter and receiver

I have a static transmitter and a mobile receiver. Is there any wireless technology to find the distance between the two in real time. Apart from using gps!
0
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1answer
123 views

GPS SOS Signal Device

Is there a way to send GPS coordinates from one device to another, without the use of any kind of cell service? What I'm attempting to design is a device that connect to a motorcycles' tip-over ...
3
votes
3answers
464 views

Does an RF receiver constantly consume power?

I'm building a battery operated robotic arm and would like to use a cheap, short distance RF transmitter/receiver kit to trigger it. However I would like to know whether the receiver will constantly ...
3
votes
2answers
129 views

Designing a Morse code transmit/receive shoe

Thank you for considering my general question, which I assure you is serious! I want to build -- or have built -- a magnificent shoe that can convert taps (front of the shoe) into Morse code and ...
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1answer
123 views

Mapping Temperature Transmitter Range: 4-20 mA to temperature Range: 0-100C [closed]

I want to know as to how do you subdivide the above range 0 C To 100 C into 4 to 20 mA.? Each mA will be of what Range in degree C.
2
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3answers
151 views

High Powered Radio Transmitters

What kind of radio transmitter would be used on an data collection unit to transmit telemetry over long distances? For example a weather station in a remote location, or in a buoy just off the coast ...
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1answer
241 views

Question about transmitter/reciever

I have built a transmitter/receiver with an antenna and crystal. I am wondering if it is stable. Here is my transmitter: simulate this circuit – Schematic created using CircuitLab Here ...
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2answers
551 views

How to make a Transmitter/Receiver [closed]

I am trying to make a transmitter and a receiver, I have two crystals and two antennas (basically a straight piece of metal with plastic covering), how could I make a transmitter and receiver with ...
0
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2answers
149 views

Checksum done without microcontroller

How could I transmit data from a device such as a distance sensor or quadrature encoder with an RF transmitter and also transmit a checksum or will I have to use a microcontroller such as the Arduino? ...