Which Antenna to be used with SIM808? Internal or External?


#1

Dear Sir,

Thank you very much to create this site to solve query related to embedded systems. I am really very happy to share my query with you.

(1).
Sir I have made GPS tracker using SIM808 and its work correctly with long wire GPS antenna. But problem is, it’s takeing more than 1 minutes to tack GPS signal with long wire GPS antenna and sometimes it’s takes more than 6 minutes. And it’s not tacking signal in house I always have to come outside of my room to take GPS signal. So how to solve this problem and I want to use internal GPS antenna. I have 3 types of antenna long wire Glonass, internal active and passive type antenna. internal antenna tack more time to take GPS signal and when we are in running mode so its never tack GPS signal if we stop bike for 20 sec then its take GPS signal so its necessary to stop our movement to tack GPS signal?
So, According to your experience which internal antenna is better to tack GPS signal in short time and can GPS antenna fetch GPS signal in house.

(2).
Diffrence betweent internal active and passive antenna to fetching signal? which one is better?


Need help in designing a GPS tracker - Battery and Antenna selection
#2

Dear Kiran,
I am glad you liked it. Just trying to build a community.

The movement is not related to GPS signal fix. Its not necessary to be stationary as GPS signals are supposed to track the movement.

The active antennas with long wires which we get in the market are better compared to internal Antenna. If you are not getting fix properly, you might not have connected the bias for the external active antenna.
Look at my post for details,

Any GPS cannot acquire fix indoors. GPS is meant for outdoors with open sky view.
And 1 minute for signal fix on a cold start is normal.

Active antennas are better at signal reception.


#3

Thank you very much for reply.
1.
Sir, its compulsory to use GNSS (Glonass) type antenna for SIM808?
2.
and sir I have used SIM808 breakout board so i think this connection of bias already is there, because i have checked it after bias its not working even not received GSM signal also and after removed bias its taking GSM and GPS signal but its tacking more time to take GPS signal. I have just connect pin 7 VDD_EXT to pin 35 GPS_RF_IN through 10ohm register.


#4

Any GPS antenna is fine. The frequency is normally written on Antenna.
Ok let me know the results. And stay outdoor in open sky view to get signal. Indoor or below large buildings you wont get signal.


#5

sir its showing me perfect location within 2 min after switch on.But problem is when i switch on it on bike in moving condition so, its take more time to get signal and some time its not getting and when i stop bike for 10 sec so its get the signal so what is problem? why its not taking signal when i am in movement?

After getting signal there is no any problem.But when we power on it so its taking 2 minute for stationary condition and when i power on it in moving condition so its take more time.
Is this an antenna’s problem or something else? I am operate it on 3.7v dc.


#6

4V is the ideal voltage for its operation. 3.7V is marginally acceptable.
The reason for getting signal after stopping might be a loose connection somewhere near Antenna. Check it once. Solder all parts or connectors properly so that nothing vibrates or gets loose.

You are using separate battery or using vehicle battery?


#7

we have check with both.With bike battery LM7805 voltage regulater we have used.


#8

7805 is 5V regulator? Are you reducing it to 4V again later?
5V will damage the module


#9


this image is taken from datasheet of this module.

Sir, SIM808 Device can work between 5v-10v. On circuit of this module one more voltage regulator also exist.


#10

Ok. then no problem.
May be Antenna is getting loose, check it once.


#11

dear sir ,
we have faced one problem with sim808 is that, when we are trying to send text sms so, there is message send successfully but we can not receive on mobile phone (mobile number also correct whn we are calling so its working fine but for message there is problem) and sms charge also get deduced from current balance of simcard. we have balance also in simcard and same code if we are use for sim 800L so its working fine and sendding OK on reply in serial monitor. And message also we can see on mobile phone where we have send it.

we have used this code .

Serial.println(“AT+CMGF=1”);//For text message
delay(500);
Serial.println(“AT+CMGS=“mobilenumber””); // use your 10 digit cell no. here
delay(500);
Serial.println(“how are you?”);
delay(500);
Serial.write(0X1A);

and mannually:
AT
AT+CMGF=1
AT+CMGS=“mobilenumber”
how are you?
Ctrl+z


#12

Hi, I have been wondering if why does my sim808 gps blink indicator don’t even light up?
Is it because it is not getting a gps reception?


#13

Please create separate thread for your queries.