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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2
votes
0answers
57 views

Does thhis crystal circuit works?

I need a tiny oscillator circuit for testing an application. Now I haven't much experience in creating oscillators so I would like to use this Collpits-circuit: I only need the carrier wave so I ...
-3
votes
1answer
41 views

RF Transceivers

I just need to send signal pulses with different duty cycle from RF transmitters of same frequency to a single RF receiver. How to differentiate the pulses from each transmitter?? Can anyone help me.. ...
-2
votes
2answers
113 views

Building an fm transmitter broadcasting simultaneously to all fm frequencies

I would like to build an FM transmitter that transmits a signal to all fm frequencies simultaneously, so that any nearby radio tuned to any frequency can receive this signal. Is it possible to do this ...
-2
votes
1answer
55 views

Wiring the antennas together in RF link 315Mhz RX and TX

I am using a 315Mhz Transmitter and Receiver RF link kit between two arduino. What happens if I wire the antennas of both RX and TX to both ends of a 1 meter long metal wire? Will using a conductor ...
0
votes
0answers
22 views

arduino pro mini downlaoding? [migrated]

I purchased the arduino pro mini atmega328 and equipped it with Ftdi breakout board with USB, a battery charging board, Wireless transmitter and a wireless receiver. I'm assuming they can all be ...
0
votes
1answer
45 views

Switching on Power to 433MHz chip

I have this 433 MHz transmitter attached to my Arduino 5v Vcc pin. I asked this question so I could deliver 12v to the transmitter chip, effectively boosting the transmitted power output, allowing me ...
1
vote
3answers
70 views

Are the same type of antennas used for receiving and transmitting?

Short version: Is the same antenna type used for transmitting as is used for receiving if the frequency is the same? Long version: My garage door opener uses 433 MHz to receive signals from the ...
0
votes
2answers
29 views

Transceiver and RF Emissions (Unintentional)

My question is simply what is RF emissions (unintentional) and how does it relate to a device (such as a smart phone) which contains a transceiver or transmitter (baseband IC) ? Which part of a RF ...
0
votes
1answer
42 views

Hacking an RC car controller to implement a joystick (PWM)

My RC car controller (transmitter) has only 4 buttons (left wheel forward /backward, same for right) I want to implement a joystick using Arduino. The Arduino will use PWM on the transmitter ...
2
votes
1answer
34 views

Questions about FM Mic Kit Schematic

I'm currently building an FM Microphone kit and I'd like to understand its operation before physically putting it together. The documentation only provides an overview of some aspects and provides no ...
1
vote
1answer
86 views

315 MHz Reciever/Transmitter Raspberry Pi

I bought a receiver and transmitter (I can't find the link, but it says FS1000A and LR1 315.00 on it). I also have a set of remote controlled wall outlets that operate on 315MHz according to the FCC ...
0
votes
1answer
56 views

RS232/RS485 Converter Circuit Receiving Problem

I'm trying to make an RS232/RS485 converter circuit. I used a circuit from http://airborn.com.au/layout/232cnv/232to485.html site and i changed some components on that circuit. Then I established my ...
0
votes
0answers
74 views

FM Transmitter, Jammer and Frequency Copying

I am trying out this FM transmitter circuit for a class project. As a test run I built this on a breadboard to see if it works. A Smartphone with FM radio was used to scan for the transmitter signal ...
1
vote
2answers
38 views

Common-Mode Voltage

I have an application which is using a differential transmitter to transmit a video signal(PAL).Transmitter is placed in a remote device which is connected through a long cable.The device is powered ...
0
votes
1answer
35 views

Locating the Origin of 2.4GHz RF Transmissions

Is it possible? How would it work? Consider IEEE 802.11 (aka.Wi-Fi); for instance. There's such an incredible amount of devices out there, measuring and reporting WLAN AP signal strength (RSSI, RCPI, ...
1
vote
2answers
73 views

Is there anyother way to construct an FM transmitter

I recently built an FM transmitter that uses a combination of coil and capacitor as an oscillator to generate the carrier frequency. I built this transmitter: Now my problem is that I find it ...
1
vote
2answers
140 views

Do commercial AM radio stations broadcast a carrier?

A possibly dumb question: I'd like to know if commercial AM radio stations broadcast a carrier tone along with signal sidebands. To ask my question is a different way; if I could measure (view) the ...
0
votes
1answer
40 views

Low-Frequency Magnetic Transmitter

I want to design a magnetic transmitter to detect a device which will be underground (1m to 7m) from surface, so I started to look at a solution and I find that a magnetic transmitter will work ...
0
votes
0answers
47 views

How to communicate my location using very low power generated using my piezoelectric material?

I have been able to charge a super capacitor of 0.1f upto 3.5V by embedding it in my shoes using some piezoelectric stacks, and now I want to use the capacitor for some emergency condition. I want to ...
0
votes
2answers
32 views

RFM only works if i touch power supply line

I have a small system with a ATtiny84 and an RFM12B module that transmits data. The thing is it only transmits when i touch both GND and +VCC.. no matter what component it is on. Do i need mere caps ...
1
vote
1answer
134 views

Orientation of ultrasonic receiver

I would like to use an ultrasonic transmitter and three receivers to be able to determine the position of the transmitter relative to the receivers. The distances to be measured are around 3-4 ft. I ...
-1
votes
1answer
41 views

Location transmitter [closed]

I want some advices about a radio transmistter,actually this radio trasmitter is more a location transmitter which transmits at about 512Hz.I want to know how could i design a transmiter and a ...
0
votes
0answers
23 views

Trying to design a Automatic Return AC Filter Roll System

I get tired of changing my home AC unit air filter out all the time so I was going to try and design a rolled filter material that would automatically spool up/down till it get clean filter material. ...
0
votes
1answer
56 views

Changing the port values inside the loop (8051)

I am using RX/TX module an ht12d/e for my project. I will make it short, in my program i am making a packet of data and sending it and the receiver is receiving it synchronously. The receiver is set ...
3
votes
3answers
602 views

FM transmitter design?

I stumbled across a relatively simple FM radio transmitter online. Credit: makezine.com I wanted to understand how it works (it is called "super simple" on the website), but several hours I have ...
0
votes
1answer
138 views

Multichannel RF transmitter design for 315MHz and 433MHz

first time designing RF, so pardon my ignorance. I want to design a ASK/OOK transmitter board operating on both 315Mhz and 433MHz ISM band frequencies. I have a MCU onboard that generates the data to ...
-1
votes
1answer
59 views

Looking for a LED transmitter/receiver package(or group of components)

I am trying to design a system that utilizes 355nm and 370nm LEDs. I want to keep their intensity stabilized at a certain value, so I want to create a feedback loop. I am using these LEDs as ...
0
votes
3answers
121 views

555 AM transmitter

I looked on instructables and I found an interesting(at least for me) AM transmitter made with a 555 timer which acts as the oscillator:http://www.instructables.com/id/555-AM-Transmitter/ Is this ...
37
votes
8answers
5k views

Can a radio transmitter somehow detect the number of receivers in its area?

During conversation, a colleague proposed that over-the-air television and radio broadcasters can determine the number of viewers or listeners based on the "load" on their signal. This seems to me ...
0
votes
2answers
304 views

Is wireless power transfer by induction at 60Hz possible, or does the frequency need to be changed?

I want to build a wireless power transmitter that works over a very short distance. Can I use my line voltage(120V at 60Hz) through the primary coil to induce voltage into a secondary coil about 1/4" ...
0
votes
1answer
20 views

ETSI Tx Power standard for short Range Devices. I am Confused

I came across the European Telecommunication Standards Institute (ETSI) standard for non specific Short Range Devices which is documented in EN 300.200 . On page 28 under Section 7.2.3 with Heading ...
0
votes
1answer
61 views

How to build a transmitter using a VCO module

this question is the consequence of my previous questions, since I am learning how RF transmitters works. In past I have also built some oscillators (using little transistors and a bunch of ...
0
votes
2answers
194 views

Make an RF transmitter: classic transistor oscillator or VCO module?

This question is about pros and cons of making an RF transmitter (eg in the FM band) in the classical way (eg. with a "transistor based" oscillator circuit, like this one which is very classic and ...
-1
votes
2answers
39 views

How to solve Power Density Function?

How to solve this problem: A radio receiver needs $$ 1 \textrm{ nW/}\textrm{m}^2 $$ of power density function, how far away from a 1-watt point source will it continue to work?
2
votes
3answers
226 views

Transmit power vs. Transmission power, is there a difference?

I was reading a scientific paper, and the authors sometimes use the term "transmit power" and sometimes "transmission power". Is there a difference in terms of correct English usage? Examples: ...
-1
votes
1answer
66 views

How do cell phones modulate transmission data

Is it digital, as in the the phone transmitter is turned on and off corresponding to the bits, or is it FM or AM? at what frequency? and how is it that they can transmit what appears to be over large ...
1
vote
1answer
74 views

How to adjust or obtain different IR Transmitter's distances?

I would like to recreate a infrared concept used by in the vacuum cleaning robot's charging station. I would like to use 3 infrared transmitters all in same wave length and transmit a synchronized ...
0
votes
2answers
116 views

How to implement TDMA with basic 433MHz transmitter receiver pairs ?

Is it possible to use TDMA or some kind of time synchronization / psuedo random coding for a number of transmitters so that they can be interfaced with a single master receiver without jamming?
1
vote
3answers
127 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 ...
1
vote
1answer
116 views

Merging right & left signals to mono with aop?

Sorry for my english i'm a young french. I want to design an audio transmitter to connect my pc to my Hi-Fi without Jack cables. For now i just want to send a mono signal because sending a stereo ...
-1
votes
2answers
258 views

Questions about FM receivers and transmitters?

I have a test tommorrow on phase lock loops, AM/FM receivers along with several other topics. I need to understand this topic clearly before I take the exam to advance to the next schooling in the ...
2
votes
3answers
162 views

What are the basics I need to know to power LEDs with RF at a range of 30 feet?

I would like to light up a path in the woods with hundreds of LEDs using RF. The idea is that I would carry a RF transmitter powerful enough to light LEDs. As I approach the LEDs would get brighter, ...
3
votes
1answer
137 views

Best communication option for multiple arduinos?

my father and I want to develop a cow pedometer to measure cows activity. The idea is that if you can measure a cow´s activity you can detect when she enters heat. Detecting heat with sensors will ...
0
votes
1answer
114 views

Can I transmit in the ISM band without a ham radio license?

I recently purchased a HackRf SDR, which has transmit and recieve capability. I'm debugging a 2.4ghz wireless module, and being able to transmit to it using the hackrf would be very helpful. Since ...
0
votes
4answers
580 views

How to build a simple LED transmitter and receiver

I'd like the distance to be about 1/10th of a mile; less distance will be fine if that's easier to build. What tools and parts may I need for this? I have plenty of LEDs lying around and I have ...
0
votes
0answers
58 views

Ultrasonic sensor pair operation

I have had success with using SR04 to measure distance from the SR04 location to nearest obstacle. Now I want to be able to measure distance of two mobile location one mounted with ultrasonic ...
0
votes
1answer
64 views

How much power does a phone consume each time it ping its SIM's ID to the nearest cell tower? [closed]

I am trying to build a device than can be tracked through the cellular network. Like a phone, for every few second the device will ping its identity to near by cell tower, which will inform the Mobile ...
1
vote
2answers
597 views

Understanding a simple crystal oscillator transmitter circuit

I've recently built this circuit: http://makerf.com/posts/mighty_simple_shortwave_transmitter It works on the desired frequency as you can see from this video : ...
-2
votes
1answer
445 views

Using HT12E/D with RX/TX 433Mhz modules

i have ht12d and ht12e ic's and rx tx 433Mhz modules. i arranged the ht12e to the output port of Microcontroller and connected the ht12e to transmitter and similarly to the recieving side. is it now ...
0
votes
2answers
79 views

How to transmit a signal to a reciever over 50 meters?

I'm studying at a technical college in Denmark, and I'm doing an exam project involving emergency calls for elders. I'm currently trying to build a solution, but it involves a transmitter which can ...