RF Remote Control and Receiver Frequently Asked Questions

Here we picked some commony asked questions by customers, regarding RF remote control transmitters and receivers, and we hope it will help our customer choose the suitable product, thanks.

1. Can multiple remote control transmitters be used nearby to each other?

Many times designers assume that because a transmitter has a unique address code or protocol that it can transmit at the same time as other units with different codes or protocols. It is important to remember that even
though the original signal may be digitally distinct, it enters airspace as an analog electrical signal. This means only one unit can operate at a time without contention. If two people are screaming at you, it does not matter what they are saying, you will not understand either one. The same idea applies to an RF receiver. While protocol or encoding is useful once a signal has been successfully received, it will not be of any use if the signal has been corrupted in the analog domain of free space. A system’s modulation method can also have an impact on its proximity. For example, in most simple AM/OOK systems, everything will be corrupt during overlapping high bit times. In an FM/FSK system, the receiver will lock onto the strongest signal and still provide usable output (assuming a reasonable differential between the two signals).

In some applications, where transmissions are infrequent and not of a critical nature, simply sending data redundantly with randomized breaks can allow the successful operation of multiple units. For applications requiring more reliable transfer, contention must be eliminated through either a sequenced network or through channelization. Either of these methods adds to system cost and complexity, but, when properly implemented, make it possible for the successful operation of multiple units without contention in the same environment.

2. Which products are FCC pre-certified?

We can make keyfob transmitters in any style and compatible with FCC transmitter requirements. all receiver relays are compliant with FCC rules, please contact us first on case by case basis.

3. Can I put my company’s logo or other marking designs on your remote control or receiver products?

Yes, products such as our keyfobs, handheld transmitters, and even antennas can be produced in custom colors and cosmetic details, such as housings or keypads, labeled to your custom requirements. There is a one-time NRE charge for setup and tooling and a minimum per order. Our graphics department can assist with your artwork if needed. Pricing is quoted on a case-by-case basis. Please contact our sales department for further details.

4. What’s the best frequency for use in my application?

315MHz is primarily used for remote keyless entry (RKE) systems and garage door openers. As a result, this frequency is somewhat crowded, increasing the chances for interference. The FCC allowed power is lower
than 418MHz or 433MHz and the selection and efficiency of antennas is limited.

418MHz is a good frequency to use in the US as it is not very crowded. This gives the least likely chance for interference and therefore the best performance, but the cost for receiver would be higher since it’s not a standard part.

433.92MHz is primarily used for RKE applications in Europe. It is also a popular frequency for active RFID tags which can have a range of up to 1000 feet. It is also good for use in the US and is recommended for most development projects.

868 – 870MHz is an unlicensed band in Europe. The band is subdivided for different applications, but there are not many restrictions on the type or duration of data. Unlike the 902MHz-928MHz band in the US, there are only 2MHz to support many applications, so the band has become somewhat crowded.

902 – 928MHz is more versatile than the 260 – 470MHz band in the US because the FCC has only specified the output power and harmonic levels. There are no restrictions on the type or duration of data that can be sent. This gives the design engineer a great deal of freedom in the possible applications, but also results in the band being more crowded. A disadvantage for cost-sensitive applications is that 900MHz modules are typically more expensive due to the more complex filtering and modulation required for link reliability at these higher frequencies.

Review rules and regulations under FCC Title 47 for more information. A resource document containing a hard copy of the application notes ships with every Linx evaluation kit. You may obtain a hard copy of FCC Title 47 from your local government bookstore or from the Government Printing Office in Washington.

5. Can I use a high gain antenna to extend the range of Solidremote receiver relays?

Of course antenna gain implies directionality, especially when receiver itself is placed behind metals that blocks wireless signal, and we offer external whip antenna as standard parts of our receiver relays board.

6. Can the transmitter or receiver boards be potted?

We do not endorse the use of any potting compound. They have the potential to affect inner component coupling, antenna match and other factors. That said, many customers use them with some success. You will want to look for one free of fillers or conductive materials. Test carefully before selecting a material or proceeding into production.