Hi there - Been using the radio dabshield. on a mega am to get work nicely but unable to pick up as many stations as the uno. Been on to the makers and the say that is down to “noise” of the mega. How can i reduce the noise ( have tried to increase the distance with jumpers wires between the board and the shield)and is there a different arduino board I acn use that has more space that I uno that has less “noise” that a mega ??
The ATmega328P processor uses more advanced chip technology than the ATmega2560, or at least that was the case in the past. Therefor the makers are probably right.
I don’t know which board has less noise.
Which DAB shield is it ?
Can you show a photo of all the boards and shield ? The cheap clones are very cheap, and they try to find the limit of what is possible. That would certainly create more noise.
A radio-enthusiast will probably tell you to make a shield, or a box around the Arduino board.
You could add capacitors and inductors to the Arduino board, to reduce the transmitted noise further.
There are prototype boards with long pins at the bottom that can be placed between the Arduino board and a shield.
Thanks for the reply have tried long pins, didn’t make a lot of difference. The shield is from https://www.dabshield.com/. The mega is “proper” one and not a cheap far eastern one.
My first Arduino project was with that DAB shield. I put a DAB radio inside a cabinet I had made in the same style as a valve radio I inherited from my dad.
I didn’t find the supplied telescopic aerial to be good enough. My finished radio has an external aerial in the loft.
I’m afraid I don’t know the answer to your question, but why do you need to use a Mega?
I am not sure of your setup but I have found the newer faster processors generate more noise because of the switching speed. Voltage has a big effect, the higher the voltage the stronger the noise signal. Try running your signals in twisted pairs where one of them is a ground connected only at one end. Vary the number of twists between connections will help. Can you add some filter caps to the mega power supply, some small MLCC type. The mega is on a larger PCB and has a lot of antennas connected to the processor, the UNO has less, that is probably the primary reason for the difference. Try to determine a frequency that its harmonics will not interfere with it and the IF. Once you know that try the arduino at that frequency if it is reasonable, That is the reason for some of the weird frequency crystals in some automotive radios.
Designing a radio shield to go on top of a ‘naked’ MCU does not sound very intelligent.
At least move the aerial away from the Arduino (with coax cable).
They say it is for a SAMD board. Can I read somewhere that a Uno or Mega is allowed ?
Is a schematic available ?
Manufacturer’s page of the Si4684: https://www.silabs.com/audio-and-radio/si468x-digital-radios/device.si4684.
Thanks for the ideas.
Using the mega for extra space, lcd etc
PerryBebbington which areial did you use ?
Will try to add some caps to the mega later on
Indeed so, RF wise the 8Mhz\16Mhz Atmel processors are some of the quietest.
I have measured the effect faster Arduinos have on LoRa reception (434Mhz) sensitivity and it can be significant.
Switching power supplies, in particular some USB power banks, can if nearby the antenna and not screened loose as much as 20dBm in sensitivity.
Or put a grounded metal foil between them, I use copper foil and masking tape to insulate both sides, it is very effective.
Is it allowed to use a Arduino Mega ? Is that somewhere on that website ? They say it is for a SAMD board (Arduino Zero, Arduino M0).
10 cm jumpers pickup digital noise , they act as antennas.
PerryBebbington - would very much like to see the code you use for your radio - could\have you put it up on the projects page ?
I’m happy to share it with you. You need to know that I used a Nextion display as the user interface, which is what you can see in the middle of the radio.
I’m not at my PC at the moment, I’ll post it when I am. Send me a PM if I forget.
I have a DAB aerial in the loft. Which one? No Idea! One bought from a DIY place. Coax cable to the radio. No noise.
And yes, SAMD based Arduino supplied by the manufacturer. I would think that a Uno would be ok though, there isn’t much for the code to do.
This is the original radio the DAB radio was based on, it was built around 1950 by a friend of my dads. I wish he were alive to see the DAB version.
Here are the Arduino files and the Nextion HMI file. I’m giving you these ‘as is’, so little support. DAB_radio_V1.zip (456.4 KB)
Hi thanks for the code, as you say quite “simple”, two other questions which amplifier did you use ( if you can remember) and how to you put the Coax cable in the radio ?
As to cutting the noise from the mega have been trying to pack it with aluminium foil and sponge which as work a little bit but will ry to improve.
Many thanks for all your help.
I used a class D amplifier board I found on your favourite retail website; there are loads of them for about £2.
Power from an old mains transformer I found, rectifier, big capacitor and SMPS to 5V and linear 15V regulator for the amplifier. Power supply all in earthed aluminium box for screening and safety.
I removed the supplied connector from the board and soldered a short piece of wire to an F type female connector with another wire for ground. Connector mounted on aluminium bracket. Whole thing mounted on earthed aluminium plate, which also holds front panel controls > Mains : Volume : input selector (cosmetic, not used yet). Aerial connector faces back of cabinet so I can connect standard coax with F type connector.
“Designing a radio shield to go on top of a ‘naked’ MCU does not sound very intelligent.”
That is true however if you look a lot of MCUs have shields like many members of the ESP families. That is the most cost effective way of meeting US radiation requirements as mandated by law. Most car radios are placed in a shield (the case) for the same reason sthomas229 states and to block outside interference. I have some of them with chokes in the power feed line. There are millions of car radios out there and they are not all the same. Some OEM radios even have traps built in to block certain vehicle electrical noise.
The thing works!
I had no issues with noise, even from the Nextion, which does generate some noise itself.