22
votes
What could this signal at 119.9 MHz be?
This signal is an extremely inefficient use of bandwidth, as you can see because there is an essentially unused area between the center and ±125 kHz. Therefore, I expect that it is almost certainly ...
- 7,581
7
votes
Accepted
10MHz reference vs 1 PPS vs GPSDO
A GPSDO is a way of providing a 10MHz reference. A GPSDO can be an external device, but some SDR devices are also able to "host" a GPSDO so that you don't need an external unit in its own ...
- 8,227
6
votes
Software Defined Radio hardware
Data rate => bandwidth.
USB will handle only a limited data rate, and the entire digitised bandwidth would have to fit into this channel.
With an FPGA at the remote end, it can crunch the digitised ...
- 174k
5
votes
High precision distance between two GPS devices (may be GNSS-SDR)
How to get 1 cm relative accuracy with GPS:
Buy a 1 cm accurate GPS receiver.
For that level of accuracy you need an RTK (Real Time Kinematic) receiver. A good system will give you 1 cm accuracies ...
- 6,992
5
votes
Accepted
Noise factor in homemade software-defined GPS receiver
Can your SDR measure signal strength at specific frequency?
If so a simple test is to measure the noise power at a frequency where no signals are present (maybe place Antenna/LNA in shielded box). ...
- 772
5
votes
Transmitting high-speed PWM over RF
The end goal is to transmit this clock and recover it at the other end, with both the phase and embedded 1PPS intact, so that it can be used for synchronization.
Then you need to have a clock ...
- 100k
4
votes
DSP on the Raspberry Pi
So, first of all, I'm biased. I maintain the GNU Radio source code.
So, what you want to do is pretty much perfectly fulfilled by GNU Radio
For flexible connection of signal processing steps, you'd ...
- 100k
4
votes
Where does SDR IQ data come from?
The "imaginary" part needs to be captured on the analog side, with a separate mixer that uses a LO source that is exactly 90 degrees offset from the "real" LO.
In the physical world, only real-valued ...
- 12.8k
4
votes
Getting started with Radio design
You'd not start by buying hardware – you'd start by
understanding how these devices work, then
implementing them in software, then
making your software fast enough to run in realtime, then
you ...
- 100k
3
votes
Accepted
Software Defined Radio hardware
Note: we're going to oversimplify SDR hardware for illustration in this answer
ADC --> PC is (one of) the functions of the FPGA
The FPGA serves different functions in different SDR designs, but one ...
- 12.7k
3
votes
Software Defined Radio hardware
Yes, it's possible, this is what the DVB receivers do. You could also do an USB 3.0 design, e.g. based on the EZ-USB FX3, these can be connected to ADCs and DACs easily, and the firmware just sets up ...
- 12.8k
3
votes
Accepted
Where does SDR IQ data come from?
Short answer: The transmitter encoder/modulator
e.g. QAM
IQ modulation is used everywhere including SDR.
Understand some roots in phone data modems since above 1200 baud then up to 56kbps/64kbps ...
- 148k
3
votes
Homemade GPS Receiver: Cascading LNAs and Band-Pass Filters?
I've connected my RTL-SDR Blog stick to a GPS antenna, and when the LNA bias is on, I see a modest increase in the noise, over the band 1565-1585 MHz. (I used some kind of scanning software, the ...
- 7,941
3
votes
IQ modulation and phasors: which first?
The fundamental motivation is: "Arbitrary AM modulation and adding two sine waves together is easy, arbitrary phase modulation is hard."
Here's the details. When we send information on a ...
- 2,116
3
votes
Can software defined radio be used as noise generator?
Could I achieve this with a software defined radio?
You can produce any band-limited signal, given its bandwidth is within the capabilities of the SDR. So, yes.
You'll find that "shortwave ...
- 100k
3
votes
What sampling rate is needed for demodulating and decoding GPS signal data?
A more detailed understanding of the Nyquist rate would show that it requires sampling at twice the information bandwidth, not the carrier frequency. In the GPS case, there is no information at the ...
- 20.3k
3
votes
Accepted
Definition and Purpose of LFTX / LFRX in SDR Hardware?
The N210 is daughterboard based. That is, the N210 itself is a fancy network connected digitizer (ADC/DAC + FPGA + ethernet interface) and it requries a front-end card for analog interfacing. In most ...
- 3,794
3
votes
Accepted
How to manage multiple devices connected to the same antenna?
A circulator is not suitable because it will only couple received RF from the antenna to the SDR -- not to the modem, which has to both receive and transmit.
If you're not trying to use the SDR ...
- 5,969
3
votes
Resource consumption of Ettus USRP devices
Power consumption: That will 100% depend on what you actually do with your signals, so this can't be a static number. This is a number logically impossible to calculate based on the image and its ...
- 100k
2
votes
"56k modem" found in VHF band
160MHz lies in the Marine VHF Radio Band.
I guess the signal you received is for the marine vessel tracking system called AIS (Automatic identification system). In section Technical Specification of ...
- 16.5k
2
votes
Antenna preamplifier
The Q2n2222 is a 2N2222 clone.
It's ancient. It was marketed as a switching transistor, the datasheets you can still find for this type of transistor usually don't even specify frequency-dependent ...
- 100k
2
votes
How can I measure my smartphone transmitted power?
How can I measure my smartphone transmitted power?
You can't.
At least not in a very meaningful way. I mean, using an SDR receiver you can get an indication of the frequency your phone is using and ...
- 81.4k
2
votes
Accepted
How do Software Defined Radios have such big bandwidth?
can scan it's whole frequency range (1MHz to 6GHz) in the same time.
How does that happen?
Not at all.
The HackRF (and other SDRs) can just be tuned to arbitrary frequencies, giving you arbitrary ...
- 100k
2
votes
Accepted
Is it possible to replicate a Novotron 522 remote control?
Unless there is an unexpected flaw in their design, it is not possible.
Rolling codes are designed so that, even if you can intercept the data frame that has been transmitted from the genuine remote, ...
- 16.2k
2
votes
Determining motor position with EMI
Think about it for a moment. Even if you know exactly how many steps the motor makes during each movement, there's no way to determine the direction of the movement from the EMI emissions. Therefore, ...
- 178k
2
votes
400Mhz frequence HackRF One
You will not be harmed by receiving radio signals on an antenna unless you are extremely close to the transmitter. In any case, those signals are present at your location whether you have a receiver ...
- 16.4k
2
votes
Accepted
Use Tx port on SDR for an LO?
Instead of sourcing an LO from a company like Wenzel, which can be expensive, could I feasibly just use this Tx as my LO? Any drawbacks to this idea?
I regularly recommend that to customers of one of ...
- 100k
2
votes
Carrier Waves, modulation over RF vs on wire
Carrier Waves, modulation over RF vs on wire
RF stands for radio frequency. A signal which has a radio frequency carrier is RF, whether it is transmitted through a wire, a waveguide, or is "...
- 27.9k
2
votes
How could you determine the point in time a Radar antenna is directly facing a stationary RF receiver station?
When you calculate a trigger level of e.g. 80% of the peak power you get two triggers per rotation around the flat high power angle. The center can be interpolatet and the precision improves, the more ...
- 8,335
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