Tagged Questions
-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.
2
votes
4answers
141 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
106 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
143 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
183 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 ...
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
147 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 ...
3
votes
1answer
86 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 ...
2
votes
1answer
138 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, ...
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 ...
1
vote
1answer
123 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 ...
1
vote
1answer
283 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 ...
-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 ...
2
votes
1answer
287 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
178 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 ...
1
vote
2answers
330 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 ...
-1
votes
1answer
226 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 ...
5
votes
2answers
1k views
Impedance Matching Differential Signals
I'm designing a circuit with RFICs using differential signaling. I'd like to keep noise to an absolute minimum. Let's use the mixer (LT5560) as an example. All of the reference schematics match to 50 ...
1
vote
2answers
213 views
Anyone know of a good/cheep usb dongle to pick up ULF (.3 - 3kHz) radio?
I've bought a pack with 3 temperature senders and 1 receiver. But I want more, and I also want datalogging.
Is there a USB dongle that let's me pick up on a given frequency, lets say '433.92 Hz' and ...
3
votes
1answer
481 views
2.4GHz Warmer/Colder game based on signal strength
I'm currently looking for options to build a 3 piece game for an outdoor activity company based around the warmer/colder game.
Two teams are each issued a receiver, and each team starts around 400
...
1
vote
1answer
123 views
Any idea on any device which track multiple mobile phones
I'm currently ask to work on a project which I have never worked before.
And I have no freaking idea or its not even in my area of expertice.
Ususally I Google as everyone does. But what is the use ...
1
vote
1answer
536 views
Building a UHF FM audio transmitter
I'd like to build a UHF (~800 MHz) FM audio transmitter. I have no experience in electrical engineering but I study physics and I'd like to acquire practical experience in electronics. In fact my goal ...
3
votes
1answer
262 views
Circuit that dumps RF energy on matched load. Can anyone help?
Background
Trying to protect my home against the RF irradiation by cellular tower nearby. Read an article that proposes 2 things:
Metal film, or fine metal mesh, which is grounded. This is used on ...
4
votes
3answers
482 views
Communication - 2 Battery Powered Circuits, 1 Conductor, no common ground
TL;DR I need to do is successfully transmit a wave across a single conductor between two battery powered circuits with no common ground. I already know how to create the wave and detect the wave when ...
-1
votes
2answers
672 views
Radio triangulation on millimeter scale plausible?
(For this question, let's throw away the skepticism of what's possible or practical today and instead focus on what's plausible in the future. This is all theoretical, but here's the idea:)
We'd like ...
1
vote
0answers
80 views
iSCSI RF-Receiver Control on Linux [closed]
I need to control a Watkins-Johnson Radio-Frequency Receiver through an iSCSI-adapter on Debian 6. What is the easiest way to achieve this? Most tutorials concern storage devices (disk drives) so I ...
1
vote
3answers
3k views
Modify an AM/FM radio to an airband receiver: What, if any, changes to the demodulation circuit?
It seems to be possible to modify a cheap AM/FM radio to receive air traffic control (ATC) communication just above the regular FM band. One range used for ATC is at 108...137 MHz.
Some quick ...
2
votes
2answers
191 views
Can you recommend a book on wireless protocol design?
Can anyone recommend a book on wireless protocol design?
I'm trying to find books with a thorough treatment of MAC and network layers without just being a guide to one specific protocol.
The kinds ...
1
vote
2answers
239 views
434MHz Noise Sources
Are there common sources of 434MHz noise or interference in a residential/household environment? I've been playing with some radios, and they seem to be behaving flakily at my friend's house even at ...
4
votes
2answers
327 views
What low power RF Transmitter to use for crowded signal area
Hi I'm fairly green when it comes to RF technology in circuits.
Here's my problem: I need a low power RF transmitter module (3 - 5v) for my application. It's a small embedded device and all it does ...
50
votes
10answers
3k views
What's the cheapest way to link a few microcontrollers wirelessly at low speeds over short distances
What's the cheapest way to link a few microcontrollers wirelessly at low speeds over short distances.
I'm looking to keep it ultra-cheap, use common discrete parts and keep it physically small. I ...
3
votes
2answers
3k views
DCF77 (AM 77.5 kHz) receiver in discrete components?
I'm looking to better understand basic RF receiver circuits, and I thought building a basic AM 77.5 kHz receiver seemed like a good challenge. I do however have had quite a challenge in finding any ...
