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CC1310 launchpad default antenna

Ahmed Mahgoub
Intellectual 825 points
Other Parts Discussed in Thread: CC1310, CC1190

Hello,

I start to progress with CC1310 launchpad. I am testing range distance with the 2 demo codes TX and RX. I need to know which antenna is by default connected in the launchpad. Is it the PCB embedded antenna or the JSC connector ? I tested the range without any external antenna and while connecting JSC cable and got only few meters !

Also, we will start to design our own custom board so we need to know a rough estimation of the embedded PCB antenna LOS range if we used this design.

Regards,

Ahmed

  • 0
    TI__Expert 6540 points

    Hi, it's by default the PCB antenna. You can check this by looking at which pads the component is mounted.

  • 0 in reply to FredG
    Intellectual 825 points
    Hi Fred,

    So why I can't get more than few meters range ?

    Ahmed
  • 0 in reply to Ahmed Mahgoub
    TI__Expert 6540 points
    That's more difficult to answer!
    So are you working with the rfpacketTx/Rx examples as is, with the default smartrf settings?
    In SmartRF Studio, can you try the continuous Tx and Rx modes? Use Tx Power = 14 dBm.
    What RSSI do you get?
  • 0 in reply to FredG
    Intellectual 825 points
    Yes I am working with rfpacketTx/Rx examples as is. I downloaded them to CC1310 launchpad (the basic one ==30$) and tracking the green and red flickering LED. So I can't know what RSSI, however I am going far with the TX till the Red LED in the RX stops that means no message received.
  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points

    You can use this () excel sheet to calculate the range. We have managed to get 20 km LOS powering the LP from a coin cell (Using the Long Range Mode settings)

    You can confirm that the PCB antenna is selected by checking that your LP looks like in the picture.

  • 0 in reply to TER
    Intellectual 825 points

    Thanks Ter,
    I have the same layout but when I checked with the DMM and found no connection between the soldering point below the 0 ohm resistor and the resistor itself. That is the case in both the launchpads I have ! Is that normal ?

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    How do you measure this? Is it possible to place the arrows between the two measurement points? If the measurement is done where you indicate with the existing arrows, is it possible to take a picture a bit more from the side showing the soldering?

    Note that the component placed is a 1.8 pF cap.
  • 0 in reply to TER
    Intellectual 825 points

    I placed the DMM on the soldering point of the resistor and the soldering point beneath it (probably the embedded antenna). From the side there is no direct connection between these 2 points.

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    So basically you have modified the Launchpad? Sometimes components start to rise to one side, typically when doing a manual soldering and care has to be taken to ensure that the soldering is good.
  • 0 in reply to TER
    Intellectual 825 points

    No i didn't solder or modify anything. I just measured with the digital multimeter ! The card came like this.

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    I'll forward this thread to the ones responsible for the LPs to see what they say.
  • 0 in reply to TER
    Intellectual 825 points
    Hello Ter,

    Any update on this issue ? For more information my LaunchPads are CC1310 LaunchPad Rev 1.4. I think there's a hardware issue with the antenna connection. May be both antennas are not connected as shown in the previous image I sent !

    Regards,
    Ahmed
  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    No, I haven't. But are you able to add some extra solder to the pads to get good connection?
  • 0 in reply to TER
    Intellectual 825 points

    I soldered the point between the resistor and the PCB antenna on both cards and still can't get more than 10 meters ! The green line in the image is where I add the solder to connect the 2 points. I feel that this components at the soldering point is not a zero ohm resistor as described in the schematic ! It doesn't give me a buzzer or zero ohm when I measure it with DMM.

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    I misunderstood slightly where you measured no connection. I thought it was between the component itself and the PCB. According to the layout files (www.ti.com/.../swrc319, see the LAYOUT.pdf file) it's a track from the component pad to the antenna. I find it difficult to understand why you should have a open here.

    To get a better view of what you see: If you place the two LPs 1 m apart and use SmartRF Studio to send a CW (tone, un-modulated carrier from the cont Tx tab) and the other one in cont Rx to read the RSSI. What is the RSSI reading in this case? Please take a screen dump of both SmartRF Studio windows and a picture of your setup. What you see is not normal and I'm trying to find out we you see what you see.
  • 0 in reply to Ahmed Mahgoub
    TI__Expert 4060 points
    Hello,

    If you haven't downloaded the design documents at www.ti.com/.../swrc319, please do so. Looking at the schematic, there are four components of interest in the area you are talking about, from the antenna to the 90-degree turn of the PCB trace. Going in sequence from the antenna, they are: C58 shunt (not mounted), R12 series component (actually a 1.8 pF capacitor), R13 (sharing one pad with R12, not mounted, this is where you place a 0-ohm resistor if you want to use the JSC connector) and C24 shunt (not mounted).

    In your earlier drawing, it is a bit difficult to say exactly where you are measuring, could you please explain again? You should be measuring continuity along the circuit trace, but not across R12, as this is not a 0-ohm resistor, but a 1.8 pF capactitor, which will block DC. If you want to use the JSC connector, you should remove R12 and place a 0-ohm resistor in the R13 position, sorry if this is not clearly explained.

    As for the poor range, it is of course possible that there is some soldering issue, but the boards are subject to RF testing in production. One interesting thing to measure would be to see what RSSI you get on the receiving board. There are many possible reasons for poor range; one could be low power, but other possibilities include frequency error or interference. There could also be a problem on the receiving board. It can be hard to debug this without specialized RF equipment, but looking at RSSI is a good first step.

    Best regards,
    Karl
  • 0 in reply to Karl T.
    Intellectual 825 points

    Thank you Karl,

    I have traced the connection and I understand it now. I think I was right about the missing connection between the R12 (1.8pF capacitor) and the PCB antenna. This was indicated by the green line I showed on the image before. I have completed this missing part by soldering in both the cards and still have the same issue with the range. If you looked at the side image I sent before placing the green line, you would probably recognize the missing solder.

    I dont have a way to measure the RSSI as this is a launchpad only not a development kit. If there is a way to use Tera term or similar to measure the RSSI please guide me to it.

    Regards,

    Ahmed 

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    Please see my previous post on how to measure RSSI by using SmartRF Studio.
  • 0 in reply to TER
    Intellectual 825 points

    Hello Ter,

    I am exploring the smartRF studio now. To be sure, I need to buy two CC debugger and connect them to the CC1310 launchpad I have now to measure the RSSI. Do you have any other suggestions for the hardware instead of the CC debugger ? 

    Regards,

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    To use the LPs with SmartRF studio the only thing you need to do is connect them to your PC with USB. Then they should pop up in SmartRF Studio.
  • 0 in reply to TER
    Intellectual 825 points

    Hello Ter,

    I used smartRF studio and connected the Tx and Rx and placed beside each other. I got steady -15dbm in the receiver side with continuous transmission from Tx. The frequency was 868Mhz

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    Did you do this with 1 m distance between the antennas? I need a known distance to compare the RSSI
  • 0 in reply to TER
    Intellectual 825 points

    They were exactly beside each other. When tested with 1m apart it gives RSSI=-30dbm and sometimes goes down till -40dbm.

    Is the PCB antenna the one connected by default in the LaunchPad ? In other post it seems you need to move the zero ohm resistor to work with the PCB antenna.

    https://e2e.ti.com/support/wireless_connectivity/low_power_rf_tools/f/155/t/474018

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    The post you refer to covers the use of external antenna on the CC1310 EM.

    I measured with a couple of LPs I have on my desk and got ~-30 dBm with 1 m distance between the LPs. This indicates that the hardware behave as expected.

    In your first post you wrote that you only manage to get a few meter of range. Are you able to do the same test using SmartRF Studio and using the Packet Rx/ Tx tabs for the range testing? Screen shots of both the Rx and Tx side in SmartRF Studio and a picture showing where you are testing would be very helpful.
  • 0 in reply to TER
    Intellectual 825 points

    Hello Ter,

    Do I need two computers for this test ? Is there a way to make the Tx works without SmartRF by downloading the code permanently to it ?

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    Yes. The point with the test is to avoid using code to just use known good software.
  • 0 in reply to TER
    Intellectual 825 points

    Hello TER,

    I replicated the same experiment using the SmartRF. The signal at 10m is around -50db,-60db using SmartRF. The transmitter was inside a building and the receiver was outside. There was a wall in between. While Using the code rfPacketRX and rfPacketTX where the led is flickering in the presence of a signal, i lost the communication !

    I have some questions here:

    1-Is this signal strength is normal ?

    2-At what level of db does the receiver stop receiving ?

    3-Why using the code rfPacketRX and rfPacketTX can't give the same performance and they lost the communication however the Tx power is the same (14db) ?

    Regards,

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    For 50 kbps with the settings given in SmartRF Studio the sensitivity is -110 dBm which means that you should be able to receive a signal down to that level.

    A wall will attenuate the signal dependent on the material. A thick concrete wall with a lot of iron inside will attenuate a lot more than a thin wooden wall so it's hard to comment on the signal strength but it looks good. Not sure why you should get issues with the code. This is staright out of the box unmodified code?
  • 0 in reply to TER
    Intellectual 825 points
    TER, I am facing the same issue ! I was measuring the continuous TX and RX. I think I was measuring noise in the receiver. When I switched to packetTX and PacketRX I can't receive any packet when I am at a distance more than 10m same as using the out of the box unmodified code ?
  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    I thought you used packet Tx/ packet Rx in SmartRF Studio to test? That was what I asked you to do.
  • 0 in reply to TER
    Intellectual 825 points
    I started with continuous RX and TX where I found -70db at 50m but it was noise. I confirmed this when I sued packet Tx/ packet RX in SmartRF studio and cant receive any package at a distance more than 10m !
  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    - What do you measure in cont Rx using SmartRF Studio if your Tx is turned off? If it's higher than -100 dBm, try a different frequency.
    - What is the RSSI just before you loose communication?
  • 0 in reply to TER
    Intellectual 825 points
    It is not turned off. I use the continuous TX and the transmitter is transmitting continuously and the receiver is showing the dbm on a graph.
    I tried different frequency and all gives me the same noisy signal between -80dbm and -90dbm at a distance of 50m. When I changed to the packet TX and packet RX and I was expecting to get received packet because I assume the signal of -80dbm is strong enough, I found no received packages at all at a distance greater than 10m !

    In the continuous TX and RX mode, I dont have a method to know if the communication is still there or I lost it. It is only showing RSSI graph that you dont know the source of the signal (noise or recevied data from TX)
  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    Please answer my questions.

    I wanted to know the noise floor on the channel you where operating on.
  • 0 in reply to TER
    Intellectual 825 points

    Setting for 779-930: 50kps, 2-GFSK, 25 KHz deviation

    I used the Continuous RX and the RSSI is giving me an oscillation between -60dBm and -80dBm without any transmitted signal. I think this is the noise floor you mean !

    Regards,

    Ahmed 

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    If you actually measure between -60 dBm to -80 dBm without any known transmitter on the noise floor is very high. Is the noise floor the same if you measure on 865 MHz, 868.3 MHz, 902 MHz, 915 MHz, 928 MHz?

    Use cont Rx without any transmitter turned on. Also try a couple of different locations. It could be that you have a transmitter for something else (LTE?) close by that bleeds into the ISM bands.
  • 0 in reply to TER
    Intellectual 825 points

    865MHz, 868.3MHz noise floor -70dBm

    902 MHz, 915MHz, 928MHz -100dBm

    I will try to replicate the test using other frequency in the 900th range and get back to you.

    Regards,

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    It would be interesting to see if you manage to get a link on the 915 MHz band and better range. Looks like you have something on your location that send a strong signal.
  • 0 in reply to TER
    Intellectual 825 points

    I tested at 928MHz and 100m including some wooden walls around the TX that is inside the office.
    @50Kbps I cant receive many packets and the CRC error is frequently appearing.
    @626bps I received around 90 packets out of 100 wit dbm in between -104 to -114 and CRC error showed up several times only mostly in the packages after 90.

    I simulated the conditions with the excel file and I found that the maximum that I can get is 363m ! That matches with my measurement taking consideration that I have some wooden walls in between.

    My question is: is it really this is the maximum range I can get from CC1310 ? I was expecting that it is a low power very long range RF chip that I can use for up to several km ! 

    If I add the CC1190 amplifier with the CC1310, how improvement in the range you would expect ?

    Regards,

    Ahmed

  • 0 in reply to Ahmed Mahgoub
    TI__Guru**** 317180 points
    Yes, you can reach several km but that require that you have line of sight and that both the Rx and Tx side is high above ground. Playing with the excel sheet shows this. Adding CC1190 will add 3 dB in sensitivity and 12 dB in output power adding about 15 dB in link budget. You can see how much this adds in range by remove the link margin that's part of the excel sheet.