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Newbie Question, range upgrade  XML
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Hopez



Joined: 08/09/2015 12:42:17
Messages: 4
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Hi, i'm new for this forum. I bought anarduino some time ago 915Mhz HW, and now i'm trying to use them.
A good thing is that they send and receive data, the bad things is that they don't communicate over 20 meters.

I use the RFM69 library, i have corrected the original baud rate using the value for 1200 baud written in the datasheet, and
i have gained some meters, but i can't reach the garden yet. There are 3 wall, and about 30 meters, between me and the garden.
I have already setted the high power command.

I use a simple iron cable for the antenna, it is long 15 cm. My question is, is it a problem of the antenna or there is something
wrong in the settings? There are a lot of parameters to set, i can reach the garden? How much can i go far with this radio?

Thank you and thanks for the answer
stevech



Joined: 07/07/2014 18:07:27
Messages: 91
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RFM69HW (high power), modest data rate and modest channel width and modulation index, clear line of sight, max TX power, expect perhaps 100-300m in the 868/915MHz ISM bands. The key is to choose the prudent predefined modulation mode from the table built into RadioHead.

This message was edited 1 time. Last update was at 08/09/2015 22:14:34

Hopez



Joined: 08/09/2015 12:42:17
Messages: 4
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Thank you for the answer, i use the simplest RFM69 library and it works well, i have tried to use the Radiohead after change the init setting to the anarduino
pin SS and IRQ pin 2, the initialization is ok, but the ping pong from server to client don't work. Is there a problem if the server is on the first floor over the
garden where ther is the client anarduino? And for 815 Mhz i should use a 33 cm antenna o a 16,5 antenna?
stevech



Joined: 07/07/2014 18:07:27
Messages: 91
Offline

Hopez wrote:Thank you for the answer, i use the simplest RFM69 library and it works well, i have tried to use the Radiohead after change the init setting to the anarduino
pin SS and IRQ pin 2, the initialization is ok, but the ping pong from server to client don't work. Is there a problem if the server is on the first floor over the
garden where ther is the client anarduino? And for 815 Mhz i should use a 33 cm antenna o a 16,5 antenna?


I'll assume your 816MHz above is a typo for 915. Don't use that in the EU. I'm not sure about UK and elsewhere.

RadioHead is the way to go. Get a pair of microprocessors w/radios working at a short range (same room). Understand how to use the APIs in RadioHead. Then go for range and unattended radios.
Choose one of the 12 or so GFSK radio configurations, say, 9600 Baud in channel about twice that wide (2x9600Hz).

Antenna.. approximately 1/4 wavelength at your radio's frequency. The RFM69HW's are sold to operate only in one of two bands: 433MHz and 868MHz (EU) + 902-928MHz in No. America. Radio has poor range if tuned to the wrong band.
Antennas for 868MHz and the 915MHz (center) can be the same.

Hopez



Joined: 08/09/2015 12:42:17
Messages: 4
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I bought for error this anarduino and only after i have seen on ebay an advice in a reseller page that says that 915 Mhz can't be used in Europe, perhaps it's used by GSM phone.
The next month i'll buy the 433 Mhz version. I'm watching the library and i see in RF69_RH that for the measuring of the output power they have connected the end of the wire
of the antenna to the ground, can be usefull to have more signal quality? or the antenna should be connected only to ANT pin?

Thank you

Hopez



Joined: 08/09/2015 12:42:17
Messages: 4
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I'm buying them, can i connect the SPI, chip select and irq to an arduino nano which works at 5 volt, using the 3.3 volt
pin for the power supply of the RFM69HCW 433 Mhz? or i should use an arduino mini which works at 3.3 volt?

sorry for my newbie questions
 
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