Consider also the rf tag.
0
votes
0answers
63 views
How to modify this circuit to transmit shortwave radio
Here is a simple beep transmitter at 27 mega hertz. How can I modify this to transmit at a lower frequency so my friend with a ham radio can hear it.
Also how can I build / where can I get the ...
-1
votes
0answers
40 views
Frequency meter application
Has anyone tried to implement a frequency counter with a maximum frequency of 50 Mhz on the beagle bone? I need to incorporate such a counter in my application.
5
votes
1answer
104 views
Variable Capacitor?
I am working on a simple FM radio transmitter and I was looking for a variable capacitor to help tune the circuit. I rummaged around and took apart an old Sony radio that had this component in it. ...
0
votes
1answer
61 views
Repair a xbee wire antenna?
last year I bought a xbee pro s2b, the wire antenna one. After some use, the antenna started to loose, and last week it just broke. Is there a way to repair it? I soldered it again, and it holded some ...
1
vote
0answers
120 views
Does living near a cell tower decrease your overall exposure to RF? [closed]
I understand that my mobile phone will increase its RF levels when it struggles to connect with a cell tower/base station due to distance. Also being nearer a cell tower will increase my exposure to ...
2
votes
4answers
140 views
Troubleshoot Crystal Radio
Alright, I'm totally confused. I have built the following circuit with absolutely no result, not even a click. Even after reading through several other similar questions on the board, I haven't ...
3
votes
3answers
105 views
Radio wave transmission and receiving antenna
When you transmit signals at radio frequency why are the antennas open ended (open circuit)? I can understand that changing the electric field causes changes in the magnetic field and hence the wave ...
4
votes
5answers
139 views
Are E and B fields in phase in electromagnetic radiation?
I recently wrote this answer, in which I said:
Radio waves are electromagnetic radiation. Electromagnetic radiation contains of two components, one electrical and one magnetic. These components ...
1
vote
2answers
175 views
Simple Morse code transceiver circuit
I want to build a portable device (handheld) that receives and transmits Morse code in the form of Radio Frequency. I want the antenna length to be 8 inches or less and would also like a range of up ...
8
votes
2answers
252 views
Is this Radio Frequency and will it work?
I really don't understand radio-frequency and how it works, and I get very confused on the theory and how an antenna etc. works. I first start with the electrical transformer. Energy is transferred ...
-2
votes
3answers
82 views
What is the radio models distance limit?
From how far could be a flying machine operated from a static station?
What is the physical limit? 1km ? 5km? or 10km?
Is the only problem of creating "drones" operated from your appartment the ...
1
vote
1answer
140 views
TinyOS interrupts handling
I'm working on a sensor project which uses TelosB based on CC2420 and MSP430F1611 running TinyOS.
The aim of the project is to measure the distance between two devices. I was thinking to measure the ...
1
vote
4answers
130 views
Radio Waves reach in function of frequency
What is the relationship between the reach of a RF signal and its frequency?
What I mean is: If power is kept constant, should I use high or low frequency waves to get a better reach? Why?
1
vote
2answers
145 views
Chip antenna mounting considerations
I'm using this chip antenna with a 868MHz radio (RFM12B): http://www.johansontechnology.com/datasheets/antennas/0868AT43A0020.pdf
According to the datasheet's mounting considerations there's a trace ...
0
votes
0answers
85 views
How can I add an external antenna to a VHF HT with no external connector? [closed]
I have a marine vhf radio I use for kayaking (http://www.midlandradio.com/Marine-Radio.O01/Nautico-1) I has no external antenna connector.
When at home I want to improve reception (not ilegal where I ...
0
votes
1answer
255 views
long wave radio receiver circuit
I wish to build a radio which can receive on 60khz am. What is the simplest circuit that will achieve this. Assuming a ferrite rod in a inductor/capacitor configuration, how would I tune this setup?
3
votes
1answer
85 views
Addressable low power radio
I want to build a Tracy Island style eyes-that-glow-when-that-person-calls project and I'm looking for advice on what components to use.
For those who haven't watched Thunderbirds, my plan is to have ...
0
votes
1answer
235 views
How to make a cw transmitter with a crystal oscillator (A0645147)?
I am trying to make a very basic cw transmitter, so far i got a 5V crystal oscillator: A0645147. Whenever I apply voltage to it i can pick up the signal on my handheld however i am not hearing the ...
2
votes
2answers
177 views
Cheap bracelet with indoor location tracking
I want to provide people at an indoor exhibition of ours with a bracelet which allows me to send a signal to it to flash a led light. At the same time I want to be able to determine the location ...
2
votes
1answer
136 views
Active 433Mhz RF tag battery life question
I am exploring the world of RTLS system and trying to produce one on my own. I chose 433Mhz frequency for its penetration capabilities and I produced a PCB mounting CC430 TI family MCU-transceiver, ...
7
votes
2answers
291 views
What do I need in order to build and test a ferrite rod antenna for a specific frequency?
I am trying to piece together what I'd need for a small hobby project. I'd like to build something that is basically the equivalent to a home made avalanche beacon finder. Avalanche beacons transmit ...
2
votes
1answer
65 views
wavelength and L/C ratio
When choosing the L/C ratio in this reference text states that you need to
choose 1.5pf for one meter wavelength. Why is that?
How that leads to have higher gain? How that leads to have a
higher ...
0
votes
0answers
83 views
Connecting IP microwave radio link directly to SerDes
Is it possible to connect RF front end (low noise block) circuit of microwave/radio antenna directly to SerDes (serial transcivers like RocketIO in Xilinx)?
I am asking since SerDes has a Data Clock ...
1
vote
1answer
122 views
Is it possible to detect a transmitter that comes within a certan range? [closed]
I know nothing of electronics. My experience is with software engineering, not electronic engineering. This is a "Is it possible?" type question. If it isn't possible, where are the barriers?
I'm ...
2
votes
1answer
156 views
How to calculate the LNB output frequency from a satellite transponder?
There's a lot of sattelite tracking sites and other information sources that give tunning information as 'Ku band, elevation NN⁰, home transponder = 11015H'.
The question is, what 11015H means?
...
3
votes
1answer
857 views
Are there any RF remote control circuits without any ICs?
I'm currently trying to make a simple 3 channels RF remote control circuit but without any ICs or micro-controller. I'm Googling but it seems to not populate (useful results). Does anyone have ideas?
1
vote
1answer
282 views
Background needed for a simple RF transmitter/receiver pair [closed]
Current background: I'm familiar with the very basics of linear circuits, and I've played around with microcontrollers a bit.
I'd like to make a simple radio transmitter and receiver for digital ...
2
votes
1answer
83 views
Video Transmitter/Receiver Books&Schematics [closed]
I'm looking to build a video/audio or just video transmitter and receiver for use in robots. I'm primarily doing it as an excercise, but I'd love to be able to get a range of 100-200 meters. I'd love ...
2
votes
1answer
158 views
A complete Radio electronics guide
I want to learn all the basics about making a simple radio project.
The project is simple... One transmitting device (which only sends out analog signals of some decent frequency.. say 50MHz) and one ...
2
votes
1answer
92 views
Building radios using RLC Meter
I'm interested in building AM and FM radios from discrete components. Has anyone ever used an RLC meter to precisely create the inductors and other elements used in these radios? I know cheaper RLC ...
2
votes
5answers
527 views
Increasing speakers impedance by adding resistors
I've got a (pretty dumb) radio which increases volume by digital dB, and not some analog device. Thus it goes something like { Mute, -75db, -65db, -56db, -49db, etc }. Now I use this radio basically ...
3
votes
2answers
81 views
Why do mobile phone transmissions come in pulses?
We are all familiar with the phenomenon that mobile phones induce in amplifiers and loudspeakers. The bip bip-da-bip bip-da-bip which happens just before you get a call, or if the phone is just ...
-1
votes
1answer
97 views
VoIP handheld device with secure point-to-point communication over WiFi [closed]
All hams on deck!
Bad joke aside, I'm in need of some suggestions. I'm working on a project and have hit a wall. I'm designing a solution that allows point-to-point wireless communication over a ...
0
votes
0answers
89 views
Simple radio switch [closed]
I'm not too knowledgeable about this, so bear with me, but I would like to build a simple radio-type device where all that it is able to do is remotely toggle something (using a transistor I suppose). ...
2
votes
1answer
286 views
Reverse-engineering RF packets
I have a Blue Line Innovations PowerCost Monitor. It sends packets to a display unit over a 433.92 MHz RF link. There is code (Power Monitor, incomplete) to detect these packets with a RF Link 4800bps ...
1
vote
1answer
111 views
Using Audio Cable to connect to computer [closed]
I have a HB100 Microwave Sensor Module which I am going to use for an experiment, and I want to transfer the data it produces directly onto my computer. Since the output of the device is in the audio ...
1
vote
1answer
176 views
Simple radio serial communication
I need a way to transfer small amount of data (4 8bit integers + checksum) over wireless.
I'm struggling to find any information dealing with sending serial transmissions over some sort of radio ...
4
votes
4answers
343 views
How can cell phones location be detected?
Specifically: cell phone not connected to internet, not used to talk, just powered
on. What if it's powered off?
1
vote
2answers
134 views
VHF: power resistor to replace dummy load
I need to check a VHF radio installation @ 155 MHz. For these purposes there exist fairly expensive dummy loads. Can I just use an ordinary power resistor soldered with short wires (3cm) to an ...
-2
votes
2answers
157 views
Radio Control Electronic Schematic
My friend, who is interested in jet engines and welding is getting is working on a jet car, or something along that lines. I am just working on the electronics because I like the circuit building and ...
1
vote
2answers
327 views
How do I change the frequency of an rf module?
I recently bought an AM radio transmitter/receiver from eBay.
It was only after I bought it, however, that I noticed that the frequency was 315/433 MHz. I live in the UK so only 433 MHz would be ...
0
votes
1answer
860 views
The appropriate code (arduino) of Xbee
Can you tell me what is the appropriate code to send two variables (x,y) from an xbee to another xbee (series 1). I configured them and i can't write a code (because i don't know how to recieve ...
-1
votes
1answer
223 views
Log Periodic antenna Design
What are the specific formulas for designing a LP antenna? Values like boom length, spacing, number of segments needed, and segment width? desired range is 500 to 5000MHz. Thanks!
0
votes
1answer
60 views
RF Antenna Frequency
I'm curious as to the ability of an antenna designed for a specific wavelength, to work on another wavelength. For example, I have a half wave antenna that is 1.5m long, which would be ideal for a ...
1
vote
1answer
117 views
Questions about RF receiver design
I'm trying to design a wide band RF receiver(say 5MHz to 5GHz).
The antenna:
How long would the antenna have to be to pick up this range?
I read that the antenna width would have to be at least as ...
6
votes
1answer
207 views
Faraday Cage - Detecting one
I am looking for a cheap and easy way of creating a small electronic device that is capable of detecting whether or not it is inside a Farraday Cage.
Hopefully, without an external sensor/emittor.
8
votes
2answers
266 views
Send GPS coordinates via VHF
I want to set up a system such that wherever a user of VHF presses the PTT button the coordinates from a GPS receiver will transmited to receiver and stored in a computer. Is that possible ? Where ...
13
votes
2answers
253 views
Why don't interfering radio stations both play at the same time?
Since radio-waves are additive, I would expect that overlapping stations (eg. two different signals broadcasting on 95.7 within range) to both play over my radio at the same time.
But that's not what ...
1
vote
1answer
185 views
How does range affect Xbee's power consumption?
I am using Xbee ZB SMT in a module, with a microcontroler and sensor, all powered by a battery.
Are there any studies on how range affects the power consumption of the Xbee module?
And as I would very ...
19
votes
6answers
2k views
What is the basic difference between AM and FM radio?
I want to know the basic/fundamental difference between AM and FM radio. Why nowadays FM radio has replaced AM and has become more popular?
